Preheat the oven to 350. Line an 8x8 baking dish with parchment paper.
In one bowl combine flour, oats and salt. In a second bowl, melt butter and whisk in granulated sugar, brown sugar and vanilla. Combine wet and dry ingredients together.
Press ¾ of the crumble mixture into the prepared pan. Spread the blackberry preserves on top and then press the remaining ¼ of the crumble on top.
Bake for 30 minutes, then let cool completely. (Once slightly cooled, refrigerate for 1 hour to speed up cooling time)
Cut into 16 evenly sized bars.
Notes
Substitutions:
Replace unsalted butter with salted and remove the ¼ teaspoon of salt.
Replace blackberry preserves with any other fruit spread of choice. Or to use fresh berries, toss them with 1 tablespoon each cornstarch and sugar and layer on top the crumble. Baking time may need to increase by 5 minutes.
Substitute half of the all purpose flour with wheat flour for a healthier take.
Use gluten free flour and oats for a gluten free variety!
Add in ¼ to ½ cup chopped nuts of your choice to the crumble (walnuts, almonds or pecans)