Preheat oven to 350. Place Cookie sheet into oven to warm.

Place room temperature butter in the bowl of a stand mixer and mix. Slowly add brown and white sugar and mix on low speed until smooth.

Mix in egg and vanilla extract until combined.

On low speed, slowly add salt, baking soda, and flour, stopping often to scrape sides of bowl. Once dough is incorporated, set aside.

Remove cookie sheet from oven and set on a towel and cover with parchment paper. Taking half or 3/4 of the dough, depending on the size of the cookie you want, place on cookies sheet. The warm baking sheet will help shape the dough into a heart easier. Press down and form heart. For bottom, make heart rounded, not a sharp point because that will burn easily. Keep it as thick as the rest of the cookie, so it cooks evenly.

Once heart is shaped, sprinkle m&m's over the top and press into dough slightly.

Place in warm oven and bake for 12-14 minutes or until sides are golden brown. Remove from oven, and let cool fully before picking it up or it will break apart.

Make a smaller heart with remaining dough, or use it for regular sized cookies.

Enjoy!