Description

Craving a warm, comforting dessert that’s bursting with tart rhubarb and a crunchy, gluten-free topping? Oat & Brown Sugar Gluten-Free Rhubarb Crisp is a delightful balance of tangy rhubarb filling and a sweet, oaty crumble, perfect for spring or summer gatherings

Ingredients

Scale

Filling

Rhubarb (scant 5 cups, 575 grams, cut into 1-inch pieces on the diagonal): The star, providing tart flavor and juicy texture; diagonal cuts add visual appeal.
Organic Cane Sugar (½ cup): Sweetens the tart rhubarb, balancing flavors.
Tapioca Starch (2 tablespoons): Thickens the filling, creating a glossy, cohesive texture; gluten-free alternative to cornstarch.
Lemon Juice (from 1 lemon, ~2-3 tablespoons): Enhances tartness and brightens the rhubarb’s flavor.
Vanilla Extract (1½ teaspoons): Adds warmth and depth to the filling.
Pinch of Salt: Elevates and balances the sweet-tart flavors.

Crisp Topping

Old-Fashioned Oats (½ cup, 55 grams): Provides chewy, hearty texture; ensure certified gluten-free for safety.
Oat Flour (½ cup, 50 grams): Adds structure and a nutty flavor; gluten-free binding agent.
Tapioca Starch (1 tablespoon): Enhances crispiness in the topping.
Raw Pepitas (¼ cup, finely ground, or ¼ cup almond flour): Adds nutty flavor and crunch; ground pepitas keep it nut-free.
Raw Sunflower Seeds (¼ cup): Contributes texture and subtle nuttiness.
Brown Sugar (⅓ cup, not packed): Brings caramel-like sweetness to the topping.
Granulated Sugar (2 tablespoons): Adds extra sweetness and crisp texture.
Fine Sea Salt (¼ teaspoon): Balances sweetness and enhances flavors.
Cinnamon (¼ teaspoon): Adds warm, spiced notes.
Unsalted Butter (5 tablespoons, melted): Binds the topping, creating a golden, crispy finish.

Substitutions and Variations

Rhubarb: Use frozen rhubarb (thawed and drained) or add 1 cup strawberries or apples for a sweeter filling (adjust sugar to ⅓ cup if sweeter fruit is added).
Cane Sugar: Swap for coconut sugar or granulated sugar; maple syrup (⅓ cup) works but may make the filling wetter.
Tapioca Starch: Replace with cornstarch or arrowroot powder (same amount) if not gluten-free.
Lemon Juice: Use bottled lemon juice or 1 teaspoon apple cider vinegar for tartness.
Vanilla Extract: Omit or use ½ teaspoon almond extract for a different flavor.
Oats/Oat Flour: Ensure certified gluten-free; swap oat flour for rice flour or more ground oats (blend oats to a powder).
Pepitas/Almond Flour: Use ground sunflower seeds, walnuts, or omit for a simpler topping (increase oats by ¼ cup).
Sunflower Seeds: Swap for chopped pecans, almonds, or omit (increase pepitas or oats by ¼ cup).
Brown Sugar: Use coconut sugar or all granulated sugar for a lighter flavor.
Butter: Replace with coconut oil or vegan butter for dairy-free; solid coconut oil may need slight warming.
Cinnamon: Swap for nutmeg, cardamom, or omit for a plainer topping.

Pro Tip: Weigh rhubarb (575 grams) for accuracy, as volume can vary; use certified gluten-free oats to avoid cross-contamination. Grind pepitas finely for a flour-like texture if not using almond flour.

Essential Equipment

9 or 10-inch Baking Dish or 10-inch Cast Iron Skillet: For baking the crisp; cast iron adds a rustic touch.
Mixing Bowls: For combining filling and topping ingredients.
Whisk: To blend dry topping ingredients evenly.
Coffee Grinder or Food Processor (optional): For grinding pepitas if not using almond flour.
Oven or Grill: For baking or grilling the crisp.
Foil (for grill): To cover during initial grilling.
Spatula or Spoon: For mixing and spreading topping.

Pro Tip: Preheat the baking dish or skillet briefly to help the filling cook evenly; use a cast iron skillet for a crispy edge.

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Instructions

Prepare for Baking:
- For oven: Preheat to 375°F (190°C).
- For grill: Turn on the left and middle burners, leaving one side unheated. Preheat to 400°F (204°C).
- Tip: Ensure steady grill temperature; use an oven thermometer for accuracy if needed.
Make the Filling:
- In a large bowl, combine scant 5 cups (575 grams) chopped rhubarb, ½ cup organic cane sugar, 2 tablespoons tapioca starch, juice of 1 lemon, 1½ teaspoons vanilla extract, and a pinch of salt.
- Stir well and let sit while preparing the topping to release juices.
- Tip: Toss thoroughly to coat rhubarb; let sit 5-10 minutes for better flavor meld.
Prepare the Crisp Topping:
- In a separate bowl, whisk together ½ cup old-fashioned oats, ½ cup oat flour, 1 tablespoon tapioca starch, ¼ cup ground pepitas (or almond flour), ¼ cup raw sunflower seeds, ⅓ cup brown sugar, 2 tablespoons granulated sugar, ¼ teaspoon fine sea salt, and ¼ teaspoon cinnamon.
- Stir in 5 tablespoons melted unsalted butter until fully combined and crumbly.
- Tip: Use a fork to mix butter for an even, clumpy texture; avoid overmixing to keep it crumbly.
Assemble the Crisp:
- Add the rhubarb filling to a 9 or 10-inch baking dish or 10-inch cast iron skillet, spreading evenly.
- Sprinkle the topping over the filling, leaving a ½-inch border around the edges to let the rhubarb peek through.
- Tip: Pat topping gently to adhere; the border ensures a pretty, bubbly appearance.
Cook the Crisp:
- Oven Method:
  - Place the dish on the middle rack and bake for 40 minutes, until the fruit is softened, bubbling, and the topping is golden brown.
  - Check at 35 minutes; cover with foil if topping browns too quickly.
- Grill Method:
  - Place the dish on the unheated side of the grill (indirect heat). Cover with foil and close the grill lid.
  - Bake for 20 minutes, then remove foil and rotate the pan clockwise.
  - Continue baking for 25-30 minutes, until bubbling and the topping is lightly browned.
- Tip: For oven, rotate halfway for even baking; for grill, check heat to maintain 400°F and avoid hot spots.
Cool and Serve:
- Let the crisp cool for 20-30 minutes to set the filling and enhance flavors.
- Serve warm with a scoop of vanilla ice cream or whipped cream (makes 6-8 servings).
- Tip: Cooling prevents burns and thickens the filling; reheat briefly if serving later.

Cooking Tips:

Check Doneness: Look for bubbling fruit and a golden topping; rhubarb should be fork-tender.
Prevent Soggy Topping: Leave the border to let steam escape; don’t pack topping too tightly.
Grill Safety: Use oven mitts and keep the grill lid closed to maintain heat; foil helps initially to cook the filling.