Preheat oven to 350ºF. Line two baking sheets with parchment paper. Place unwrapped chocolate Kisses or hearts into the fridge or freezer while preparing the cookie dough.
18 unwrapped Hershey's Kisses or Dove Hearts
In a larger mixing bowl, beat sugar and butter until light.
2/3 cup granulated sugar, 1/2 cup salted butter
Add egg, vanilla, and red food coloring. Mix again, stopping to scrape the bottom and sides of the bowl.
1 large egg, 1 teaspoon vanilla extract, 1 Tablespoon red gel food coloring
Add flour, cocoa powder, baking soda, and salt. Mix again on low speed until combined.
1 2/3 cups all-purpose flour, 1 Tablespoon cocoa powder, 1/2 teaspoon baking soda, 1/4 teaspoon salt
Scoop heaping tablespoonfuls of dough onto prepared baking sheets and roll into smooth balls. Space them about 2 inches apart so they have room to spread while they bake.
Bake in center of oven for about 10 minutes, until edges are set, but centers are still soft.
Remove from oven and press an unwrapped heart into the center of each cookie.