Preheat oven to 350°F. Grease two 8-inch cake pans and line with parchment. Whisk flour, baking powder, baking soda, and salt in a bowl.

Beat butter until smooth, add sugar, and cream on medium-high until pale and fluffy, about 3 minutes. Add eggs one at a time, then mix in vanilla and rosewater.

On low, add dry ingredients in three parts, alternating with buttermilk, starting and ending with dry. Mix just until combined.

Divide batter between pans. Bake 25–30 minutes, until a toothpick comes out with a few moist crumbs. Cool in pans 10 minutes, then turn out onto a rack to cool completely.

For the buttercream, beat butter until smooth. Gradually add powdered sugar, then vanilla and 3 tbsp cream. Whip until light and spreadable, adding more cream if needed.

Place one layer on a plate, spread with jam, then a cup of buttercream. Top with second layer. Crumb coat the cake and chill 20 minutes. Frost with remaining buttercream and press fresh edible flowers onto the surface.