1. Prepare Jam and Oven:

Preheat oven to 350°F (175°C).

Line 16 standard muffin cups with paper or foil liners.

Gently warm the ½ cup of seedless strawberry jam (a few seconds in the microwave or over low heat) until slightly loosened. Press the warm jam through a fine-mesh sieve into a small bowl, discarding any pulp or seeds left behind. Set the strained jam aside.

2. Cream Butter and Sugar:

In a large bowl, using an electric mixer, cream the softened butter and granulated sugar together until light and fluffy, about 5-7 minutes. Scrape down the sides of the bowl occasionally.  

3. Add Egg Whites and Flavor:

Add the room temperature egg whites, one at a time, beating well after each addition until fully incorporated.

Beat in the strained strawberry jam (reserving ¼ cup for the frosting!) and the vanilla extract.

4. Combine Remaining Wet & Dry Ingredients:

In a small bowl, whisk the milk and sour cream together until smooth.

In another medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

5. Alternate Wet and Dry Additions:

With the mixer on low speed, add the dry ingredients to the creamed mixture alternately with the milk/sour cream mixture. Begin and end with the dry ingredients (add dry, then wet, then dry, then wet, then dry).

Beat well after each addition, but only until just combined. Do not overmix.

If desired, stir in a few drops of red or pink food coloring.

6. Fill Liners and Bake:

Fill the prepared muffin cups about three-fourths full with batter.

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

7. Cool Cupcakes:

Let the cupcakes cool in the pans for 10 minutes.

Then, carefully remove them from the pans and transfer them to wire racks to cool completely. Cupcakes must be completely cool before frosting.

8. Make the Whipped Cream Frosting:

In a large, chilled bowl, beat the cold heavy whipping cream with an electric mixer until it begins to thicken.

Add the confectioners’ sugar, the reserved ¼ cup of seedless strawberry jam, and the vanilla extract.

Continue to beat on medium-high speed until stiff peaks form. Be careful not to overwhip, or it will turn buttery.

9. Frost and Garnish:

Spread or pipe the strawberry whipped cream frosting over the completely cooled cupcakes.

If desired, garnish with fresh strawberry slices or halves.

10. Store and Serve: Refrigerate any leftover cupcakes due to the whipped cream frosting. Enjoy!