- 1 cup old-fashioned rolled oats
- 1 cup all-purpose flour
- ¼ cup granulated sugar
- ¾ cup brown sugar
- 1 teaspoon ground cinnamon
- ⅔ cup unsalted butter, melted
- 1 large crisp apple, cored and chopped - I used a Honeycrisp
- ½ cup chopped rhubarb - optional
- 4 cups frozen berries - I used raspberries, blackberries and blueberries
- ¼ cup granulated sugar
- ½ teaspoon lemon juice
- 1 teaspoon vanilla extract
- 1 tablespoon cornstarch mixed with 2 tablespoons cold water
Make the topping first by combining the oats, flour, sugar, brown sugar, cinnamon and salt. Stir to combine. Pour in the melted butter and stir to incorporate. Store the topping in a mason jar sealed with a tight-fitting lid. Refrigerate in the coldest part of your refrigerator until ready to use.
To make the fruit filling, add the chopped apple, frozen berries, granulated sugar, lemon juice and vanilla extract to a medium saucepan. Heat over medium-high heat until the mixture is hot and just beginning to bubble. Add the cornstarch slurry and stir gently until thickened. Allow the mixture to cool before storing in a mason jar sealed with a tight=fitting lid. Refrigerate in the coldest part of your refrigerator until ready to use.
To assemble, preheat your oven to 350° F. Pour the fruit filling into an 8x8’’ or similar size casserole dish or pie plate. Sprinkle the topping ingredients evenly over the top.
Bake for 40-45 minutes until the topping is golden brown and berries are bubbling around the edges. Remove from the oven, place on a wire rack, and allow to cool for at least 7-10 minutes before serving. Serve with a scoop of vanilla ice cream, if desired.
Cover any leftovers and store in the refrigerator for up to 5 days. The premade topping and filling can also be stored in the refrigerator prior to baking for up to 5 days.
- Yields: 6-8 servings - though you can make individual servings by assembling in individual ramekins - you may wish to reduce the baking time by up to 10 minutes if you use this option
- Preparation Time: 30 minutes plus baking time, which can vary depending on container size