1. Prepare the Biscuit Base

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. Mix Dry Ingredients: Sift the flour, powdered sugar, and baking powder together.
3. Whisk Eggs: In a separate bowl, whisk the eggs until fluffy and pale. Gradually add the sugar and whisk until it reaches soft peaks.
4. Combine: Fold in the dry ingredients and melted butter gently to avoid deflating the eggs.
5. Bake: Spread the batter onto the prepared baking sheet and bake for 10-12 minutes, or until the top is lightly golden and a toothpick comes out clean.
6. Cool: Allow the biscuit to cool completely before using it as the base for your entremet.

2. Prepare the Caramel Mousse

1. Make the Caramel: In a saucepan, combine the sugar and water and cook over medium heat until the sugar melts and turns amber in color. Watch carefully to avoid burning. Once it reaches a golden color, remove it from the heat.
2. Add Cream and Milk: Gradually add the heavy cream and whole milk to the caramel (it will bubble up). Stir until smooth, then return to low heat to combine fully. Remove from heat and add the vanilla and butter.
3. Bloom the Gelatin: If using powdered gelatin, sprinkle it over a small amount of cold water to bloom. Once bloomed, add it to the warm caramel mixture and stir until dissolved. Let it cool slightly.
4. Whip the Cream: Whip the heavy cream to soft peaks and fold it into the caramel mixture. Set aside to chill.

3. Prepare the Coffee Mousse

1. Dissolve Coffee: Dissolve the instant coffee in the hot water and let it cool to room temperature.
2. Bloom the Gelatin: As with the caramel mousse, bloom the gelatin in cold water. Then, add it to the cooled coffee mixture, stirring until dissolved.
3. Whip the Cream: In a separate bowl, whip the heavy cream with the sugar to soft peaks, then fold it into the coffee mixture. Stir until smooth and well combined.

4. Assemble the Entremet

1. Prepare the Molds: Line your entremet mold (or individual rings) with plastic wrap or use a silicone mold.
2. First Layer (Caramel Mousse): Pour the caramel mousse into the bottom of the mold and smooth it out. Freeze for 30 minutes to allow it to set.
3. Second Layer (Coffee Mousse): Once the caramel mousse is set, gently spread the coffee mousse on top, smoothing it out evenly. Freeze for another hour.
4. Add Biscuit Base: Cut a circle of the biscuit base to fit the mold and place it on top of the coffee mousse layer. Chill for another hour or until fully set.

5. Glaze the Entremet

1. Prepare the Coffee Glaze: In a small saucepan, combine water, coffee granules, sugar, and gelatin. Heat gently, stirring until dissolved. Once it cools to room temperature, pour it over the chilled entremet, covering it completely. Allow it to set in the fridge for 1-2 hours.

6. Unmold and Garnish

1. Unmold the Entremet: Gently remove the entremet from the mold, being careful not to damage the sides.
2. Decorate: Garnish with shaved chocolate, cocoa powder, caramel shards, or fresh coffee beans for that extra touch of elegance.