2. In a large bowl combine the rhubarb, granulated sugar, Apple Pie Spice and 3 tablespoons of flour. Toss to coat.
3. Place the fruit mixture in a greased pie dish or 8x8 baking dish.
4. Make the crumble- In the same mixing bowl combine brown sugar, the remaining 1 cup of flour and the oats. Add in the butter. Using your fingers work the butter into the flour mixture until it resembles peas.
5. Sprinkle the crumb mixture over the rhubarb. Bake on a cooking sheet with foil for 45 minutes or until bubbling. Cool on a wire rack.
LIKE: Better Batter and King Arthur Gluten Free Multi-Purpose Flour. HINT: If using King Arthur Gluten Free Multi-Purpose Flour or a custom blend, you will need to add Xanthan Gum. Cookies/Bar Cookies, Breads, and Pizza use 1 teaspoon of Xanthan Gum for every 1 Cup GF Flour. If using Better Batter, you will need increase the liquid in the recipe by 50%. Add in small amounts until the desired moisture is reached.
OTHER: Brown Rice, Oat, Tapioca, Buckwheat, Almond, Teff, and Sorghum Flour.
Do not use quick cook oats. If using unsalted butter, add in 1/2 teaspoon salt to the crumble mixture.