Grease the pan with extra butter and dust with flour, tapping out the excess. Alternatively, line with parchment paper.

Soften the butter in the microwave for about 20 seconds. Warm the milk in the microwave and dissolve the instant coffee and cocoa powder in it.

Chop the chocolate bar.

Sift together the ★ ingredients.

Preheat the oven to 320°F (160°C).

Cream the butter with a whisk until smooth. Mix thoroughly.

Add the sugar to the butter and mix well with a whisk until combined.

Gradually add the beaten egg to the mixture in about four parts, mixing vigorously with a whisk each time to prevent separation.

Add the sifted ★ dry ingredients to the mixture and gently fold with a spatula until just combined. Do not overmix. It's ready when there are no visible traces of flour.

Add the ☆ coffee mixture and vanilla extract, mixing until smooth. Mix from the bottom to ensure no lumps remain, but do not overmix.

Add the chopped chocolate to the batter and gently mix until evenly distributed. The batter should be smooth.
The batter is ready!

Pour the batter into the pan. Slightly indent the center. Tap the bottom of the pan on the counter to remove air bubbles. Bake in the oven at 320°F (160°C) for about 35 minutes.

Once baked, remove from the oven and drop the pan from a height of about 10 inches to release steam.

Remove from the pan and cool on a wire rack. Once cooled, wrap in plastic wrap to keep it moist. Let it sit overnight for best results.

Dust with powdered sugar if desired.

Slice and serve. It's easier to cut cleanly if you let it cool completely before slicing.

I tried baking it in a paper mold for gifts.