In a medium saucepan over low heat, combine the sweetened condensed milk, white chocolate chips, and semi-sweet chocolate chips. Stir continuously for about 5–7 minutes until the mixture is fully melted and smooth.

Remove the saucepan from heat and stir in the vanilla extract, mixing thoroughly.

Prepare a greased and lined 8x8-inch pan for pouring the fudge mixture. Pour the smooth chocolate blend into the pan.

Before the fudge sets, generously sprinkle Christmas sprinkles over the top and press them gently into the surface.

Place the pan in the refrigerator for at least 1 hour, allowing the fudge to firm up completely.

Once set, remove it from the refrigerator and cut it into even squares.