Preheat oven to 190C (375C). Line standard muffin tin with paper liners. Sift flour, baking soda, baking powder and salt.
In a mixing bowl, cream butter and sugar until pale and fluffy. Reduce speed to low. Mix in peanut butter, add eggs one at a time, beating until each is incorporated, scraping down sides of bowl as needed.
Mix in vanilla extract. Add flour mixture gradually and mix well to incorporate. Mix in sour cream and peanuts.
Divide batter evenly among lined cups, filling each ¾ full. Bake at 190C for 20 min until a cake tester inserted in centers comes out clean.
Cool down cupcake completely and frost with creamy peanut butter frosting. Leave a small well in the middle of the cupcake. Add a dollop of strawberry jam into each well.
Creamy Peanut Butter Frosting
Cream cream cheese and sugar together until pale and fluffy.
Add peanut butter and vanilla extract and mix until well blended.
In a separate bowl, whip heavy cream until medium / stiff peaks are formed.
Fold the whipped cream into the cream cheese mixture.
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