Preheat your oven to 350°F (175°C). Brush a thin layer of oil on a glass baking pan. You can also grease or line a baking dish with parchment paper.
In a large mixing bowl, combine the glutinous rice, salt, cocoa powder, granulated sugar, and baking powder. Stir until well mixed. Set aside.
In a separate mixing bowl, add the melted butter, milk, egg, and vanilla extract, and mix until well combined.
Gradually add the dry ingredients mixture to the wet ingredients mixture, mixing until just combined. Be careful not to overmix.
Pour the brownie batter into the greased or lined baking dish. Gently spread it out evenly using a spatula.
If desired, sprinkle chopped nuts, chocolate chips, or other add-ins over the mochi layer. I did not.
Bake the mochi brownies in the oven for approximately 1 hour or until a toothpick inserted into the center comes out clean.
Remove the brownies from the oven and let them cool completely in the baking dish. Once cooled, cut the mochi brownies into squares or desired shapes and serve.
Enjoy your homemade mochi brownies!