Heat the oven to 425ºF. Put the beets in a small baking dish and add water to come ½ inch up the sides. Cover the dish tightly with foil and roast the beets until a knife slides easily in and out of one, 50 to 60 minutes. Remove them to cool completely in the dish.
When completely cool, cut off the ends and slip off the skins. Transfer the flesh to a food processor and puree it until very smooth, scraping down the sides once or twice. You should have about ¾ cup of beet puree. Add the jam, buttermilk, eggs, vanilla extract, and ¼ cup of oil; puree until smooth, 15 seconds.
Whisk together the all-purpose flour, oat flour, baking powder, and salt in a large bowl. Add the wet ingredients and stir just until combined.
Warm a griddle or large skillet over medium heat. Coat it lightly with oil and drop about 3 tablespoons of batter into the skillet for each pancake. Cook until lightly browned, about 4 minutes per side. (To minimize browning and preserve the pink color of these pancakes, they are cooked over slightly lower heat and for a slightly longer time than typical pancakes.)
Tip: Look for oat flour in the baking aisle or natural foods section of your grocery store. Or make it at home by grinding about 1 cup of old-fashioned rolled oats in a food processor until reduced to ¾ cup of powdery flour.