1-Preheat oven to 350F: Preheat oven to 350F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.
2-In a large, microwave-safe bowl melt the: In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
3-Wait momentarily before adding the egg so: Wait momentarily before adding the egg so you don’t scramble it. Add the peanut butter, egg, brown sugar, vanilla, and whisk until smooth.
4-Add the flour, salt, and stir until: Add the flour, salt, and stir until just combined, don’t overmix.
5-Stir in 1 cup chocolate chips: Stir in 1 cup chocolate chips.
6-Turn batter out into prepared pan, smoothing: Turn batter out into prepared pan, smoothing the top lightly with a spatula.
7-Sprinkle evenly with 2 tablespoons chocolate chips,: Sprinkle evenly with 2 tablespoons chocolate chips, smooth the top lightly with a spatula.
8-Bake for about 20 to 25 minutes,: Bake for about 20 to 25 minutes, or until done. A toothpick inserted in the center should come out clean, or with a few moist crumbs, but no batter. Allow bars to cool in pan for at least 30 minutes before slicing and serving.
9-Bars will keep airtight at room temperature: Bars will keep airtight at room temperature for up to 1 week, or in the freezer for up to 6 months.