Cream the butter, olive oil, and sugar together until smooth. Add the vanilla and the eggs, one at a time, until fully incorporated and then add the sour cream and mix on low until smooth.
Slowly add the flour until just barely mixed. Combine the oats with the baking powder, baking soda, and spices in the bowl of a food processor and pulse until the oats are finely ground. With the mixer on low, add the oats, scraping down the sides until everything is just barely combined. Stir in the plums.
Spray 2 9-inch loaf pans with cooking spray, cover the bottoms with parchment paper, and spoon the batter evenly between the two. Bake at 375 degrees until a toothpick inserted into the center comes out clean, about 45 minutes. Let cool in the pans and then invert to remove the loaves.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2014/10/spiced-sour-cream-plum-bread/