Preheat the oven to 350ºF. Line 15 muffin cups with paper liners. Set aside.
In a large mixing bowl whisk together the melted butter and sugar. Beat in the yogurt. Add the eggs one at a time, beat well after each addition. Beat in the vanilla.
In a medium mixing bowl combine flour, baking powder, baking soda, and salt. Gradually add flour mixture to butter mixture alternating with milk. Begin and end with flour mixture. Mix until well blended.
Spoon batter into prepared pans, filling each cup 2/3 full. Bake for 25 minutes or until a wooden toothpick inserted into the center comes out clean. Remove cupcakes immediately from pans, and cool on a wire rack.
To make the frosting
Beat butter on medium speed until fluffy. Gradually beat in powdered sugar until light and fluffy. Beat in milk until frosting reaches spreading consistency. Stir in the strawberry jam. Frost the cupcakes, garnish with fresh strawberries, and enjoy.
Make ahead tip
Cupcakes will keep for up to 5 days stored in the refrigerator.
The plain cupcake can be made 1 day in advance. Cover and store at room temperature.
The frosting can be made 1 day in advance. Cover and store in the refrigerator until ready to use.
Both frosted and unfrosted cupcakes can be frozen for up to 3 months. Thaw in the refrigerator overnight.