Heat the oven to 375°F and cover cookie sheets with parchment paper. Parchment prevents sticking and helps the cookie bottoms brown evenly.
Beat the peanut butter, softened butter, granulated sugar, brown sugar, and salt in a large bowl or stand mixer fitted with the paddle attachment until creamy and blended. The mixture should look lighter and fluffy rather than dense or greasy.
Mix in the room-temperature egg and vanilla, scraping down the bowl so no buttery streaks remain. A smooth, uniform mixture helps the finished cookies bake with an even texture.
Add the flour and baking soda, then mix on low only until the dry flour disappears. Stop as soon as the dough comes together to keep the cookies tender.
Roll the dough into 1-inch balls, coat them in additional granulated sugar if desired, and arrange them 2 inches apart on the prepared sheets. Even portions bake at the same pace and leave room for the cookies to spread gently.
Bake for 8 to 10 minutes, then press one unwrapped chocolate kiss into the center of every cookie as soon as the sheets come out of the oven. The tops should look pale and puffy with fine cracks, while the bottoms should be just beginning to brown.
Leave the cookies on the pans until completely cool and the chocolate centers have set. The kisses will soften from the cookie’s heat but should retain their defined shape.