Put 1/2 cup chocolate in a small microwave-safe bowl with the food coloring and 1 teaspoon oil. Put 2 cups chocolate in a medium microwave-safe bowl with 1 teaspoon oil. Microwave each bowl in 30-second intervals, stirring in between each, until melted, 2 to 3 minutes. Stir 2 tablespoons chopped chocolate into the small bowl of red chocolate and the remaining chopped chocolate into the medium bowl of plain/white chocolate. Let stand 5 minutes, then stir until smooth.
Line a baking sheet with parchment and scatter with the crème de menthe pieces. Pour over the white chocolate and gently spread until smooth and even. Dollop with the red chocolate and swirl the red into the white with the tip of a paring knife. Scatter with the peppermint puffs and sprinkles. Tap the sheet several times on the counter to settle. Cool until hardened, about 1 hour.