Whisk together the dry ingredients in a medium-sized bowl and set aside.
Preheat your oven to 350℉. Line an 8x8-inch baking dish with parchment paper, leaving parchment paper overhanging the edges for handles, and set aside.
Prepare the Chocolate Batter
Place the butter and chocolate chips in a medium-sized saucepan. Melt over low heat, stirring until combined thoroughly. Remove from the heat.
Stir in the brown sugar and the molasses until completely combined.
Beat the eggs into the batter thoroughly.
Stir the dry ingredients into the chocolate batter until combined, with no visible flour streaks. Do not overmix.
Bake
Pour the batter into the prepared pan. Bake for 20-30 minutes, or until a toothpick or cake tester inserted in the center of the brownies comes out with only a few crumbs, but no wet batter.
Remove the brownies from the oven and cool. Once cool, remove them from the pan using the parchment paper handles.
Prepare the half batch of frosting, then frost the top of the brownies, adding sprinkles if desired. Slice and keep in a sealed container in the refrigerator if frosted, or at room temperature if unfrosted for up to 3 days,
Notes
Store in a closed container at room temperature for up to 3 days, or freeze in a freezer-safe container for up to 3 months.