Ultimate Fudgy Brownies without Eggs

Preheat the oven to 325º F (165 º C). Line an 8x8-inch baking pan with parchment paper. Lightly spray with baking spray.

Combine flour, cornstarch, baking powder, and salt in a bowl. Set aside.

In a mixing bowl or liquid measuring cup, combine the milk and vinegar. Let the mixture rest for 5 to 8 minutes, until thickened and curdled.

Melt butter in the microwave. Alternatively, you can do it over the stovetop in a medium saucepan.

Stir in the sugars and mix until well combined, for about 2 - 3 minutes. The mixture must be homogeneous and glossy, not oily.

Add milk mixture to the butter mixture; mix with a whisk to incorporate. Microwave the mixture for 2 minutes. Carefully remove the bowl from the microwave and continue mixing with the whisk for 1 – 2 minutes. Undissolved sugar will prevent you from getting the crackly top on the brownies, so rub a little of the mixture between your first finger and thumb to test. If it feels smooth with no grains of sugar, it's ready. If you can feel some grains, place the mixture in the microwave and heat for 1 more minute, and then mix with the whisk for 1 -2 minutes. Repeat until you don’t feel any grain of sugar at all.

Add cocoa powder, and mix to incorporate; continue constantly stirring for 2 more minutes. Add vanilla and instant espresso powder (if used), and mix to incorporate.

Add the flour mixture; stir until mostly combined. Then add the chocolate chips (reserve 1/4 cup for the top if desired) and stir until no flour remains.

Pour the batter into the pan. Use a spatula to spread it to the edges of the pan and smooth the top. Tap the pan once or twice on the counter to settle any air pockets; you can also poke the air pockets with the tip of a knife or toothpick. Top with more chocolate chips or chunks, if desired.

Bake for 40 – 50 minutes or until the brownies are set and the tops or cracked and shiny. You'll notice the center does not wiggle when the pan is moved. If in doubt, it's better to underbake these brownies rather than overbake them. Unfortunately, the toothpick test doesn't work well for these brownies because the chocolate chips get melty! IMPORTANT: Every oven is different, so baking times always have to be taken with a grain of salt. Oven thermostats can be wildly off, and that will all affect baking time.

When the brownies are ready, remove them from the oven and set the pan on a wire rack until completely cooled.

When completely cool, run a thin knife around the edge of the pan to make sure the block of brownies is loose, then lift from the pan using the parchment paper sling. Cut the brownies into 9 or 12 squares.