Prepare the Rice Cooker: Lightly grease the inner pot of your rice cooker with butter or cooking spray.
Mix Dry Ingredients: In a large bowl, sift together the flour, cocoa powder, baking powder, and salt.
Mix Wet Ingredients: In another bowl, whisk together the melted butter and sugar until well combined. Add the eggs and vanilla extract, and mix until smooth.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, alternating with the milk. Stir until just combined.
Add Chocolate Chips: Fold in the chocolate chips if using.
Cook: Pour the batter into the prepared rice cooker pot. Close the lid and set the rice cooker to the "Cook" setting. Cook for about 40 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Cool and Serve: Once done, remove the inner pot and let the brownies cool for about 10 minutes. Carefully invert onto a plate, slice, and serve.