Preheat the oven to 350ºF and set oven racks to the middle. Line two mini muffin pans with cupcake liners. Alternatively, you can spray the muffin pans with cooking spray.
Make the flax egg by mixing together flax meal and water. Set aside.
2 tbsp flax meal, 2 tbsp water
In a large bowl, whisk together the flour, cocoa powder, baking powder, sugar, and salt. Whisk away any clumps of flour.
½ cup all purpose flour, ¼ cup cocoa powder, ¾ cup granulated sugar, ½ tsp baking powder, ¼ tsp salt
Make a well in the middle of the dry ingredients and pour in the plant milk, melted butter, apple sauce, and flax egg.
¼ cup unsweetened plant milk, ¼ cup vegan butter, ¼ cup unsweetened apple sauce
Use a spatula to beat the batter for 1min, or until the batter is smooth and thick.
Add the chocolate chips and mix until they are evenly distributed in the batter.
⅓ cup vegan chocolate chips
Divide the brownie batter between the mini muffin cups. Top each mini brownie with one ¼ piece of Oreo, or one mini Oreo.
6 oreos cut into quarters
Bake for 15-20mins. A toothpick inserted should come out clean, or with minimal brownie crumbs (not wet batter).
Allow the brownies to cool in the pan for at least 10mins before carefully transferring to a cooling rack to cool completely.