Tired of staring sadly at all the treats you can’t have in the Starbucks glass case? These gluten free blueberry oat bars, with an oat-shortbread crust, a thick layer of blueberries (fresh or frozen) and a crispy crumb topping, make it all better.
Whether it’s blueberry season or not (as I type this, it’s no!), this recipe for Starbucks-Style Gluten Free Blueberry Oat Bars is not something you should be without for much longer. If you are going to take an Alice Watersesque stand against eating fresh blueberries out of season (I salute you!), just use frozen blueberries (don’t defrost them).
The crust is like an oat-shortbread. It’s buttery and kinda crumbly, with the slight chew of oats mixed in. The crumble topping is just what you’d expect from the perfect texture of a nice crumble topping—but studded with oats.
And can you see how the blueberries keep their shape? That’s because the crust doesn’t take long to bake. And since we want to keep the crumble topping from browning too much, we just don’t bake the whole thing for too long not too long at all. Frozen berries will leak a bit more than fresh ones, but even the frozen ones should hold their shape relatively well.
Preheat your oven to 325°F. Grease a 9-inch square baking pan, and line with crisscrossed sheets of unbleached parchment paper to make it easy to lift the bars out of the pan after baking. Make the crumble topping. Combine all of the topping ingredients (8 tablespoons butter, 1/2 cup all purpose flour and xanthan gum, rolled oats, granulated and brown sugars, and salt), and blend with a fork until well-combined. Place in the refrigerator to chill until ready to use.
Make the crust. In a large bowl, place the all purpose flour, xanthan gum, oat flour, salt, baking powder and granulated sugar, and whisk to combine well. Add the oats, and mix to combine. Create a well in the center of the dry ingredients, and add the butter, egg and 1 tablespoon water, and mix to combine. The dough will be a bit dry, and you will have to knead it with your hands to get it to come together. If necessary for the dough to hold together, add a second tablespoon of water, 1 teaspoon at a time. Transfer the dough to the prepared baking pan, and press firmly into an even layer on the bottom of the pan. Cover with another sheet of unbleached parchment paper and smooth out the dough by pressing it down evenly. Place the pan in the center of the preheated oven and bake for 5 minutes.
While the crust is parbaking, in a small bowl, place the blueberries, sugar, oat flour and salt, and toss to combine. After the crust is done parbaking, remove the pan from the oven and spread the blueberries out on top of the crust in a single, even layer. Remove the crumble topping from the refrigerator and fluff it with a fork to break it up into irregular pieces. Sprinkle the crumble topping in an even layer on top of the blueberries. Return the pan to the oven, and bake until the crust is beginning to brown around the edges, a toothpick inserted into it comes out clean and the crumb topping is very lightly golden brown (about 17 minutes).
Remove the pan from the oven and allow to cool completely in the baking pan before lifting the bars out of the pan with the parchment paper. Slice into 8 to 12 equal pieces, depending upon how large you’d like the bars.