Preheat your oven to 350°F and line two baking sheets with parchment paper to prevent sticking and ensure even baking.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until thoroughly combined, then set this mixture aside.

In a larger bowl, using a hand mixer or stand mixer fitted with the paddle attachment, beat the softened butter with both sugars on medium speed for 1-2 minutes until the mixture becomes light and creamy. Add the egg and vanilla extract, blending until everything is well mixed, scraping down the sides of the bowl as needed. Gradually incorporate the dry ingredients on low speed until just blended, careful not to overmix.

With a spatula, gently fold in the M&M's and chocolate chips. Start with about one heaping cup mixed into the dough, reserving the rest for decorating the tops of the cookies.

Using a cookie scoop or spoon, portion out dough balls that are about 1½ to 2½ tablespoons in size. Lightly press a few extra M&M's onto the top of each dough ball, then carefully press the top of each ball into the reserved bowl of M&M’s to add a colorful topping. You can bake the cookies immediately for a thinner texture or chill the dough balls in the fridge for 15 minutes to achieve a thicker, softer texture.

Place the dough balls on the prepared baking sheets, leaving space between each for spreading. Arrange the dough mounds so they are slightly taller than they are wide to ensure they bake into a thicker cookie.

Bake in the preheated oven for 8-11 minutes, keeping an eye on the edges—they should set while the centers remain slightly soft for a tender, chewy texture. See note for tips on shaping the cookies right after baking.

Transfer the baking sheets to wire racks and allow the cookies to cool completely, letting them firm up as they cool. Enjoy these delightful treats!