Melt the white chocolate in a bowl.

Add the hot espresso and stir until smooth.

Add the cold whipping cream and mix well.

Cover with plastic wrap.

Refrigerate for 2-3 hours.

Whip until firm before using.

Bring the whipping cream just to a boil in a saucepan.

Remove from the heat.

Pour the hot cream over the chocolate to melt it.

Stir until smooth and glossy.

Add the cold whipping cream and mix well.

Cover with plastic wrap.

Refrigerate for 2-3 hours.

Whip until firm before using.

Preheat the oven to 170°C (338°F).

Line a flat baking sheet with parchment paper.

Mix the oat milk and lemon juice together.

Set aside to thicken.

Whisk together all the dry ingredients.

Sift the dry ingredients.

Prepare the vegan meringue.

Adjust the quantity as needed.

Pour the oat milk and lemon mixture into the dry ingredients.

Add the melted vegan butter.

Mix until smooth.

Gently fold the meringue into the joconde batter in two additions.

Spread the batter on the sheet in a 1/2 cm (0.2 in) layer.

Bake for 14 to 16 minutes, or until lightly golden.

Let the sponge cool before cutting.

Bring the water and sugar to a boil in a saucepan.

Remove from the heat.

Stir in the instant coffee powder.

Set aside.

Heat the whipping cream in a saucepan until it just begins to boil.

Remove from the heat.

Pour over the chocolate.

Blend with an immersion blender until smooth and glossy.

Cover.

Keep warm.

Cut the joconde into three 24 x 24 cm (9.5 x 9.5 in) squares, the same size as the square metal mold.

If you're using different-sized molds, cut the sponge layers to fit.

Place one sponge layer in the bottom of the mold.

Generously soak with coffee syrup (1st layer).

Spread the chocolate ganache evenly over the sponge (2nd layer).

Place the second sponge layer, soaked with coffee syrup, on top (3rd layer).

Spread half of the whipped coffee ganache over the top (4th layer).

Place the third sponge layer, soaked with coffee syrup, on top (5th layer).

Spread the remaining whipped coffee ganache over the top (6th layer).

Spread the whipped chocolate ganache over the top to form the 7th layer.

Smooth the top with an offset spatula.

Remove any excess ganache from the sides.

Freeze for at least 2-3 hours.

Bring the whipping cream and glucose to a boil in a saucepan.

Remove from the heat.

Pour the hot cream over the dark chocolate.

Blend with an immersion blender to remove any air bubbles and smooth the glaze.

Warm the glaze to about 40°C (105°F) before using.

Place the frozen opera on a wire rack.

Coat the top with a thin layer of warm dark chocolate glaze.

Remove the metal cake mold.

If needed, freeze for 30 minutes to set the glaze before slicing.