Preheat oven to 375℉/190℃ and line a muffin tin with liners and set aside.
Add flour, baking soda, baking powder, cinnamon, and salt into a bowl and stir, then set aside.
2 cups all-purpose flour, 1/4 tsp salt, 2 tsps baking powder, 1 tsp baking soda, 1/2 tsp cinnamon
Into a large bowl, add the oil, brown sugar, white sugar, and peanut butter. Whisk until well combined.
1/2 cup oil, 3/4 cups dark brown sugar, 1/4 cup white sugar, 3/4 cups creamy peanut butter
Add in the eggs and vanilla, then continue whisking, scraping the sides of the bowl as needed, for another minute or so until well combined.
1 tbsp vanilla, 2 large eggs
Whisk in the sour cream and milk until smooth.
3/4 cups full-fat sour cream, 1/4 cup milk
Combine the dry and wet ingredients together until a soft muffin batter forms.
Fill the muffin liners halfway, then scoop about 1/2 tsp of jam and swirl it in. Add more batter on top, then swirl more jam on top. (see photos above for reference).
1/2 cup strawberry jam*
Bake the muffins for 25-35 minutes or until a toothpick inserted comes out clean. Allow to cool, and enjoy!