Line 2 cupcake tins with liners and preheat the oven to 375 F.
In a mixing bowl whisk together 2 cups all-purpose flour, 1 cup granulated sugar, 1 Tablespoon baking powder and ¼ teaspoon salt.
In a separate mixing bowl, use a hand mixer to mix together 1 cup whole milk, warm, 1 cup creamy peanut butter , 1/3 cup vegetable or canola oil, 2 large eggs and 1 teaspoon vanilla extract.Add the dry ingredients into the peanut butter mixture and use a spoon to mix until just combined.
Fill each cupcake liner 1/3 full of batter. Add about 1-1.5 teaspoons of grape jelly on top of the batter followed by enough batter to fill the tin about 2/3 full. Dollop an additional 1 teaspoon of grape jelly on top of the batter. Use a toothpick to swirl the jelly on top around a bit.
Bake on the middle rack for about 15-18 minutes or until a toothpick inserted comes out clean (jam may stick to it but the muffin itself should not have wet batter on the toothpick.)NOTE: Oven times can vary so please go by doneness NOT just by time.
Remove from the oven and let sit on a wire cooling rack in the muffin tin for 5 minutes before removing the muffins to a finish cooling on the wire cooling rack.
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.
Warm milk and room temperature eggs helps the batter mix together much, much easier. It is not absolutely necessary though. To warm the milk, just pop it into the microwave for a few seconds at a time. You don't want it to boil, just slightly warm to the touch.