Preheat the oven to 375°F. Line a baking sheet with parchment paper and lightly spray the top of parchment.
In a large bowl, cream the butter and confectioners powdered sugar together until smooth and creamy.
Add in the flour and salt.
Use a spatula to finish mixing the dough together.
Use hands to gently knead the dough just enough to form a ball.
Add the M&Ms and sprinkles.
Use hands to mix them into the batter.
Measure 1 Tbsp of cookie dough and roll into a ball between your hands. Place on the baking sheet.
Bake for 10-12 minutes. Remove from oven and let cool on baking sheet for another 10 minutes.
Roll each ball into powdered sugar.
Place on a rack to cool completely.
Once completely cooled, roll in powdered sugar again for an even coating.
Store in an airtight container on the counter or in fridge for up to 1 week.These cookies store well in the freezer. After thawing, roll in more powdered sugar before serving.