Preheat Oven and Line Tin:

Preheat the oven to 350°F (175°C) and line a cupcake tin with liners.

Mix Sugar and Oil:

In a large bowl, mix together granulated sugar and vegetable oil until combined.

Add Eggs and Extracts:

Add eggs, vanilla extract, and peppermint extract (if using), mixing until smooth.

Stir in Sour Cream:

Stir in the sour cream until well combined.

Whisk Dry Ingredients:

In another bowl, whisk together the flour, baking powder, and salt.

Alternate Dry and Wet:

Gradually add the dry ingredients to the wet ingredients, alternating with the milk, mixing until just combined.

Tint Batter Green:

Add electric green gel food coloring to achieve desired green color.

Fill Cupcake Liners:

Pour the batter into the cupcake liners, filling each about 2/3 full.

Bake Cupcakes:

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Cool Completely:

Let the cupcakes cool completely before frosting.

Beat Butter and Sugar:

For the frosting, beat the cold unsalted butter until creamy, then gradually add the powdered sugar and mix until smooth.

Add Extracts and Salt:

Add vanilla extract, peppermint extract (if using), and a pinch of salt, then mix until combined.

Tint and Decorate Frosting:

Use green gel color to tint the frosting and decorate the cooled cupcakes as desired.

Top with M&Ms:

Top with M&Ms for a festive touch.