Place jar of Skippy Natural Dark Chocolate Peanut Butter Spread in the freezer to chill for at least 2 hours, or overnight.
Preheat oven to 350F. Spray a Non-Stick 12-Cup Regular Muffin Pan extremely well with cooking spray; set aside. I don't like the cosmetic look of paper liners because of ridges they leave, and haven't tested the recipe with them and am unsure if they will stick.
To the bowl of a stand mixer fitted with the paddle attachment (or large bowl and electric hand mixer), cream together the first 6 ingredients (through vanilla) on medium-high speed until light and fluffy, about 5 minutes.
Stop, scrape down the sides of the bowl, and add the flour, baking soda, optional salt, and mix on low speed until just incorporated, about 1 minute; don't overmix.
Using a 1/4-cup measure, portion out the dough, into 12 equal-sized mounds. Dough is very soft, squishy, and the mounds look large, but are lightweight for the size.
Roll each mound between your palms to create round, smooth globes, and set them on a plate or flat work surface.
Remove Skippy Natural Dark Chocolate Peanut Butter Spread from freezer and using a 1-teaspoon measure, scoop out rounded teaspoons, and place one teaspoon of chocolate on top of each mound of dough.
Gently push the chocolate peanut butter down into the dough mound, and use your fingers to carefully stretch up the sides of the dough to fully encase the Dark Chocolate Peanut Butter. Make sure it's fully encased so it doesn't leak while baking. Repeat for all 12 mounds.
Place one mound in each of the cavities of the prepared pan.Bake for about 14 to 16 minutes (I baked for 14 1/2), or until tops are just set; making sure not to overbake because cookies will continue to cook in pan (carryover cooking) while they cool. Allow cookies to cool in pan for about 15 to 20 minutes, or until firm enough to remove.
To dislodge cookies if you're having any trouble, gently run the tip of rubber spatula or plastic knife around the rim of the cavity; a sharp knife will scratch your pan. Or, invert the pan and tap the bottom and they'll pop out. Cookies will keep airtight at room temperature for up to 5 days or in the freezer for up to 6 months. Unbaked cookie dough mounds can be stored airtight in the refrigerator for up to 5 days, or frozen for up to 4 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.