Preheat your oven to 325°F (163°C). Coat a mini muffin tin with cooking spray.

In a mixing bowl, whisk together the cake mix and all-purpose flour. Add melted butter, egg, egg yolk, and vanilla extract, mixing until a soft dough forms.

Roll about one tablespoon of dough into a ball and place in the muffin tin.

Bake for about 14 minutes until puffy and slightly cracked on top.

Immediately press a small utensil in the center of each cookie to form a cup. Let cool in the pan for 5-10 minutes.

In a microwave-safe bowl, combine white chocolate chips and heavy cream. Microwave until smooth, stirring in 30-second intervals.

Fill each cookie cup with the ganache, distributing evenly.

Press one whole M&M in the center of each filled cookie for the bunny face and two half-M&Ms for the ears.

Let the cups sit at room temperature for about 2 hours until the ganache firms up.