Line an 8x8 or 9x9 square baking dish with parchment.

Add the semi-sweet chocolate chips, half of the sweetened condensed milk, and 1 tbsp. butter to a microwave-safe bowl.

Microwave for 30 seconds and stir well. If not fully melted, microwave 15 seconds more and stir. Stir in 1 tsp. vanilla extract.

Spread the chocolate fudge mixture evenly into the bottom of your baking dish.

Refrigerate for 30 minutes.

Add the white chocolate chips, remaining sweetened condensed milk, and 1 tbsp. butter to a microwave-safe bowl. Repeat the melting process and stir in 1 tsp. vanilla extract.

Layer the white chocolate fudge over the chocolate layer.

Sprinkle Christmas sprinkles over the top.

Refrigerate for at least 4 hours or overnight.

Cut into squares and enjoy.