Mint and Chocolate Fudge Oreo Bars

For the Crust

Oreo cookies (I used chocolate-filled; original/white-filled may be substituted; Mint-filled could cause bars to become overly minty)

tablespoons unsalted butter, melted (3/4 of one stick)

For the Mint and Chocolate Fudge Layers

heaping cup white chocolate chips (or about 7 ounces white chocolate, chopped)

heaping cup semi-sweet chocolate chips (or about 7 ounces semi-sweet or dark chocolate, chopped)

sweetened condensed milk, divided

peppermint extract, or to taste* (make sure to read caveat below)

about 5 drops green food coloring, or as desired

sanding sugar or sprinkles for dusting top, optional