Line a 9x9 square baking pan with plastic wrap. Melt 1 cup chocolate chips according to package directions. Pour chocolate into pan and smooth with the back of a spoon. Tap or gently shake the pan to help chocolate settle. Set pan in the freezer for chocolate to harden.
Melt butter and 1/4 cup chocolate chips in the microwave in 30 second intervals, stirring after each, until completely melted.
Whisk in sugar, vanilla, and salt. Add cocoa powder and flour; stir to combine.
Spread brownie batter over hardened chocolate in pan. Melt remaining chocolate chips and pour over brownie batter. Smooth out with a spoon. Sprinkle with holiday sprinkles, candies, or more chocolate chips.
Cover and place pan in the refrigerator for 1 hour, or until chocolate has set. Break into piece and enjoy!