Cut parchment paper to fit the baking pan. Fold it into a square, then a triangle, and trim the edges to create a handle. Unfold and place it in the pan.

Measure the flour and butter. Add 1 tsp of baking powder to the flour in a plastic bag and set aside.

Soften the butter at room temperature and mash it well. Add the eggs and mix until smooth.

Add cocoa powder to the flour mixture. Shake the bag to mix or sift it for a finer texture.

Combine the dry ingredients with the butter and egg mixture. Mix gently in a figure-eight motion until just combined.

Pour the batter into the prepared pan lined with parchment paper.

Cook on the lowest heat setting on a stovetop for 25 minutes with the lid tightly closed. Block any steam holes if present.