Preheat the oven to 350°F (176°C) and grease a muffin pan with cooking spray. Swirl a paper towel around the inside of each muffin cup to evenly distribute the grease and dab off any excess.
In a medium bowl, whisk together the flour, baking powder and salt.
In a large bowl, cream the peanut butter, sour cream and sugars until smooth and fluffy. Beat in the egg until incorporated, and then mix in the vanilla.
Gradually mix in the flour mixture on low speed until just combined, alternating with the milk. Begin and end with additions of the flour mixture.
Spoon a small amount of batter into each muffin cup, about 1/4 full. Top with 2 teaspoons of jam or jelly and then cover with the remaining batter. Each muffin cup should be almost full.
Bake for 20 to 22 minutes, or until a toothpick inserted into the center of a center muffin comes out clean. Let the muffins rest in the pan for 3 minutes before removing to a wire cooling rack. Store in an airtight container.