Chocolate Cake with Strawberry Mousse

Instructions

For the Chocolate Cake:

1. Start by lining a 7-inch (18cm) round cake pan with parchment paper and set it aside. 
2. Preheat the oven to 350°F (180°C) for about 5 minutes before baking the cake. 
3. In the bowl of an electric mixer, combine the eggs and sugar, then beat on medium speed for 5-7 minutes until the mixture becomes light and fluffy. 
4. Add the yogurt, vegetable oil, and vanilla, and whisk everything together. 
5. Sift the flour, cocoa powder, baking powder, and salt over the mixture, and gently fold them until just combined. Be careful not to deflate the eggs. 
6. Pour the batter into the prepared pan and bake for 25-30 minutes until a toothpick inserted into the center comes out clean. 
7. Allow the cake to cool completely at room temperature.

For the Cocoa Syrup (optional):

1. Combine the hot water, sugar, and cocoa powder. Whisk until completely dissolved and let it cool completely before using. 

For the Strawberry Mousse Filling:

1. Combine the chopped strawberries, sugar, and lemon juice in a large saucepan. Cook over medium heat for about 10 minutes, stirring occasionally, until the mixture thickens. Make sure there's no liquid left in the mixture, then transfer it to a bowl and let it cool for a few minutes until slightly warm. 
2. In a small bowl, sprinkle gelatin over water, stir until completely dissolved, and let it sit for 2-3 minutes until it becomes a gel. Microwave the gelatin for 10 seconds to melt it without overheating. Do not overheat, or the gelatin will lose its setting power. 
3. Whisk together condensed milk and melted gelatin (slightly warm) in a separate large bowl. Stir in the strawberry mixture and set it aside to cool at room temperature. Do not refrigerate. 
4. Beat cold heavy cream until stiff peaks form, then fold it gently into the reserved strawberry mixture in two or three additions.

Assembling the Cake:

1. Level the top of the cooled cake and cut it into two equal rounds. 
2. Place the first cake layer onto a serving plate and tightly adjust an acetate collar around the cake.
3. Sprinkle syrup all over the cake (optional).
4. Spread half of the strawberry mousse over the cake, then place the second cake layer on top, sprinkle some syrup, and finish with the remaining mousse. 
5. Refrigerate the cake for 4-6 hours or until the mousse is firm.

For the Chocolate Ganache:

1. Combine the chopped chocolate and heavy cream in a medium bowl. Melt the mixture using a double boiler or microwave in 30-second intervals, stirring until smooth. 
2. Let it cool for a few minutes at room temperature, then spread the ganache over the mousse layer. 
3. Place some fresh strawberries on top. 
4. Refrigerate the cake for 30-40 minutes to allow the ganache to firm up. Keep the cake refrigerated until serving time. Before serving, remove the acetate collar.