In a medium mixing bowl, whisk together flour, soda and salt; set aside. With an electric mixer, beat butter and sugars until light and fluffy. Add egg and yolk, then peanut butter, then vanilla; beat just until well combined. Add dry ingredients; beat on low speed just until you can no longer see flour. Mix in chocolate. Drop 24 evenly sized rounded spoonfuls (or use a #40 cookie scoop) 2" apart on 3 parchment-lined baking sheets; sprinkle with salt. Bake pans one at a time in a preheated 350° oven until just barely set and slightly puffy (7-9 min.), rotating pan halfway through. Cookies will appear slightly underbaked when done. Cool completely on pans set on wire racks.

Good to Know:

• For the most beautiful cookies, lightly press a few chocolate pieces into the dough balls just before baking.
• Find Kowalski's Refrigerated Peanut Butter in the Dairy Department.