Let’s build this beautiful Strawberry Chocolate Mousse Cake:

1. Make the Chocolate Cake Layer:

Preheat oven to 350°F (175°C). Grease a 9-inch regular round baking pan (NOT the springform yet), line bottom with parchment, grease parchment.

In a large bowl, stir together dry cake ingredients: sugar, flour, cocoa, baking powder, baking soda, salt.

In a medium bowl, whisk egg, milk, oil, and vanilla. Add wet to dry, mix on medium speed 2 minutes. Slowly stir in boiling water/coffee until combined (thin batter).

Pour into the prepared 9-inch pan. Bake 25-35 minutes until toothpick is clean. Cool 10 mins in pan, then invert onto wire rack, remove parchment, cool completely.

2. Prepare Gelatin (Two Batches):

In a small dish, sprinkle 1 teaspoon gelatin over 1 ¼ tablespoons (half of the 2.5 Tbsp) cool water. Let bloom 1 minute.

In another small dish, sprinkle the remaining 1 teaspoon gelatin over the remaining 1 ¼ tablespoons cool water. Let bloom 1 minute. Set both aside.

3. Prepare Chocolate Base for Mousse:

In a heat-proof bowl, combine chopped semi-sweet chocolate, white chocolate, and butter.

Melt over a double boiler (bowl over simmering water) or in microwave (50% power, short bursts, stir often) until smooth.

Heat the first bloomed gelatin dish (microwave 8-10 secs) until liquid. Stir into melted chocolate mixture. Set aside to cool until lukewarm.

4. Make Stabilized Whipped Cream for Mousse:

Heat the second bloomed gelatin dish (microwave 8-10 secs) until liquid. Let cool slightly.

In a large, chilled bowl, beat 1 ¾ cups heavy cream and vanilla extract with an electric mixer until medium peaks form.

Gradually add powdered sugar while beating.

With mixer on low, slowly drizzle in the cooled liquid gelatin from the second dish. Increase speed and beat just until stiff peaks form. Do not overwhip.

5. Combine Mousse:

Stir a few large spoonfuls of the stabilized whipped cream into the cooled melted chocolate mixture to lighten it.

Transfer the lightened chocolate mixture into the bowl with the remaining stabilized whipped cream.

Gently fold with a spatula until evenly combined and no streaks remain. Be careful not to deflate the mousse.

6. Prepare Springform Pan and Strawberries:

Clean your 9-inch springform pan. Place the cooled chocolate cake layer flat in the bottom. Set the ring around the cake. (Optional: Line sides with parchment or acetate cake collar for easier release).

Cut stem ends of strawberries flat. Cut enough berries in half vertically to line the inside edge of the pan, placing them cut-side against the pan wall, snug against the cake base.

Fill the center area inside the strawberry ring with whole strawberries, standing them up close together. Trim bottoms more if needed so all berries are roughly the same height, slightly below the pan rim.

7. Add Mousse and Chill:

Transfer the prepared chocolate mousse to a piping bag (optional, but helps fill gaps).

Carefully pipe or spoon the mousse into all the gaps between the strawberries, ensuring no air pockets remain.

Spread the rest of the mousse evenly on top of the strawberries, smoothing the top surface.

Place in the fridge for 4-6 hours, or preferably overnight, until the mousse is completely set and firm.

8. Make Ganache:

Once mousse is set, make the ganache. Place 5.5 oz chopped chocolate in a heatproof bowl.

Simmer ⅔ cup heavy cream in a small saucepan. Pour hot cream over chocolate. Let sit 2 minutes.

Whisk gently until ganache is completely smooth and glossy. Let cool slightly until thickened but still pourable.

9. Top with Ganache:

Spread the slightly cooled ganache evenly over the top of the set mousse cake (still in the springform pan).

Place back in the fridge until the ganache has set (at least 30-60 minutes).

10. Release and Make Curls:

Run a thin knife or offset spatula carefully around the edge between the mousse and the springform pan ring. Release and remove the ring.

Make chocolate curls: Melt 3.5 oz chocolate with 1 tbsp shortening/oil until smooth. Spread very thinly onto the back of a cool baking sheet. Freeze 6-8 minutes until just hardened but not brittle. Let sit at room temp 1-2 mins. Use a metal spatula held at an angle to scrape across the chocolate, creating curls.

11. Decorate and Serve:

Gently arrange the chocolate curls on top of the ganache. Garnish with additional fresh strawberries if desired.

Keep refrigerated. Let sit out briefly before slicing with a hot, clean knife. Serve chilled.