Preheat oven to 325 degrees. Line a loaf pan with parchment paper or spray with cooking spray. Set aside.
In a small bowl, whisk together the flour and baking powder. Set aside.
In the bowl of a standing mixer, beat the butter and sugar on medium speed until smooth, about 2 minutes.
Add the eggs one at a time, beating well after each addition.
Reduce speed to LOW and slowly add the flour mixture, scraping down the sides and beating until smooth.
Add the buttermilk and lemon cream or curd. Mix until combined.
Transfer the batter to the prepared loaf pan and bake for 55 - 60 minutes or until a toothpick inserted in the middle comes out clean.
Dust with powdered sugar before serving.