Line a quarter sheet tray with parchment or a silicone mat. Set aside.

In a large bowl, whisk together sweetened condensed milk and peppermint oil.

Gradually add confectioner’s sugar, 1/2 cup at a time, using your hands or a bench scraper to work the ingredients together until a soft dough forms. Dough should be smooth and pliable, but not sticky. You might not need all of the confectioner’s sugar.

Divide dough into 2 portions. Keep about 3/4 of the dough white. Into the smaller portion, knead 2-3 drops red gel food coloring or green gel food coloring.

Divide both portions in half. You should now have 2 large white portions, and 2 smaller colored portions.

Wrap 1 portion of each color dough in clingfilm/plastic wrap. Set aside.

Lightly dust countertop with confectioner’s sugar. With your hands, roll each of the remaining portions into 10-inch ropes.

Twist the white rope and the colored dough rope together.

Roll on countertop to form a smooth, thick rope, about 12-14 inches long and 1-inch thick.

With a sharp chef’s knife, trim the ends, then slice into 1/2-inch pieces.

Arrange peppermints, flat sides up, on prepared tray.

Repeat with remaining dough.

If desired, dust mints with edible glitter.

Allow soft peppermints to sit uncovered at room temperature for 8-10 hours or until dry to the touch. Use a small stepped palette knife to flip the mints halfway through to ensure that they dry evenly on both sides.

Store soft peppermints in an airtight container at room temperature for up to 3 weeks.