1Preheat your oven to 350°F (175°C) and grease an 8-inch square baking pan.
In a medium bowl, whisk together the flour, baking powder, salt, cocoa powder, and chili powder. Set aside.
In a small saucepan, melt the butter with the bittersweet chocolate over low heat, stirring until smooth. Remove from heat and let cool slightly.
In a large bowl, beat the eggs with the sugar and vanilla extract until light and fluffy.
Gradually fold in the melted chocolate mixture into the egg mixture.
Sift the dry ingredients into the chocolate and egg mixture and fold until just combined. Do not overmix.
Pour the batter into the prepared baking pan and smooth the top with a spatula.
Bake in the preheated oven for about 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.
Allow the brownies to cool in the pan on a wire rack before cutting into squares and serving.