Line a baking sheet with wax paper. In a microwave-safe bowl, microwave your yellow candy and coconut oil in 30-second intervals until completely melted. Mix thoroughly.
Submerge each cookie into melted candy, ensuring that it is completely enrobed. Carefully lay each covered Oreo onto your lined baking sheet.
Place eyes in the center of each candy-covered Oreo. You can alternate between placing two eyes or one eye.
Using an electric mixer, mix together butter, sugar, and milk. Mix on high until buttercream forms stiff peaks.
Add 2 small drops of black gel food coloring to the buttercream and fold until completely colored (it should be grey in shade). Set aside ⅓ of the grey buttercream mixture in a small bowl.
Place the rest of your buttercream in a piping bag and carefully frost around each of your Minion’s eyes. These will act as their goggles. Next, frost two straight lines on each side of their eyes.
Take the remaining buttercream (ie.: your small bowl that was set aside) and add 2 more small drops of black gel food coloring. Your buttercream should be black or dark grey in shade. Place in a frosting back and frost hair on each of your Minions.