1 cup unsalted butter (softened)
3/4 cup granulated sugar
1 cup light brown sugar, packed
2 large eggs
2 tsp vanilla extract
3 cups all-purpose flour
1 tsp baking soda
1 tsp salt
1 cup chocolate chips
1 cup M&Ms, plus more for topping
Preheat oven to 375°F.
Line two baking sheets with silicone mats or parchment paper.
In a large bowl, cream butter, brown sugar, and granulated sugar for 1 minute.
Add eggs and vanilla. Mix to combine.
Add flour, baking soda, and salt. Mix to combine.
Fold in chocolate chips and M&Ms.
Refrigerate dough 15–60 minutes (up to 24 hours).
Scoop ~3 tbsp dough balls 2 inches apart on the sheets.
Top with extra M&Ms if desired.
Bake 7–10 minutes, until edges are barely golden brown.
Cool on pan 2 minutes, then transfer to a rack.
Store in airtight container for up to 3 days.