For the cake

1. Preheat oven to 180C or 350F. Line the bottom of a 9-inch/23 centimeter springform pan with parchment paper and butter the sides. Set aside.
2. Melt chocolate and butter together. You can do this in a heatproof bowl suspended over a pan of simmering water or in the microwave in 30 second increments, stirring between each one.  Set aside to cool a bit.
3. In a large mixing bowl, whisk together eggs and sugar with an electric mixer until it becomes pale and foamy and has approximately tripled in size. This foam is what will make your cake rise, so give it time to get good and frothy.
4. Combine your ground almonds and cocoa powder, then gently fold them into your egg and sugar foam. Next, fold in the chocolate mixture. Finally fold in the lime zest and juice.
5. Pour your cake batter into your waiting pan and bake for 35-40 minutes. You'll have a firm crust on top, but it may still be a tiny bit wobbly underneath.
6. Allow your cake to cool completely. Run a thin knife around the edge of the cake before releasing the collar. Sprinkle with powdered sugar if you like.

For the Margarita Cream

1. Combine lime juice, tequila, and triple sec on a medium mixing bowl. Whisk in the powdered sugar to dissolve. Add the cream, and whisk until stiff peaks form. I did this by hand, but an electric mixer would make it go more quickly. It may take slightly longer than normal because of the added liquid.
2. Top each slice of cake with billowing clouds of margarita cream. Be sure to store any leftovers in the fridge.