Preheat oven to 350° F. Grease or paper line a standard-size muffin pan with 12 wells. Set aside.

Whisk flour, baking soda, baking powder, and salt in a medium bowl and set aside.

Whisk buttermilk, sugar, egg, butter, and vanilla in a medium bowl until well combined. Add 1/2 cup peanut butter to the mixture, whisking until well incorporated.

Use a spatula to mix in dry ingredients and about half of the peanuts until just combined, making sure to scrape up from the bottom.

Divide batter equally between muffin cups; they will be quite full. Grease a small spoon. Dip the spoon into each mound of batter, twirling and pressing down to create deep wells in the centers (the spoon may require wiping and re-greasing as the batter is quite sticky).

Fill each well with a generously rounded teaspoon of jam. Add about 1/4 teaspoon creamy peanut butter to the jam (the peanut butter will resist sticking to the jam, so it works best to attach it near the batter's edge).

Swirl the jam and peanut butter together with a skewer. Sprinkle remaining chopped peanuts over the top of the muffins, pressing them in gently to adhere.

Bake until a skewer inserted into a muffin near the edge of the filling comes out mostly clean, about 15 to 20 minutes. Cool on a wire rack for at least 5 minutes before removing muffins from the pan.

Pile the peanuts that fall off the muffins into the centers, where the filling will settle slightly. Serve warm or at room temperature.