Preheat oven to 325°. Line 16 muffin cups with liners. Beat butter and sugar with a stand mixer until creamy. Add eggs, vanilla, and buttermilk; beat until well blended.
Whisk together flour, baking powder, baking soda, and salt in a bowl. Gradually beat into butter mixture until well blended.
Whisk together jam and rose water to taste in a small bowl. Spread 2 heaping tbsp. batter in each liner. Top with 1 tsp. jam mixture, then another 2 heaping tbsp. batter, carefully spreading it to cover jam.
Bake cupcakes until a toothpick inserted toward the edge comes out clean, 25 to 27 minutes. Let cool in pans 5 minutes, then transfer to racks to cool completely. Spread with frosting and decorate with rose petals.
These cupcakes turned out really good and were pretty easy to make. The rose flavor is very light and they aren't super sweet so it was a nice balance. Perfect for a girl baby shower or a spring party. Everyone loved them!