For the Crust
1 Cup skin-on hazelnuts
3/4 Cup almond flour
2 Tablespoons granulated sweetener of choice*
1/2 teaspoon sea salt
1/2 Cup (8 tbsp/1 stick) chilled unsalted butter or coconut oil, chopped into pieces
For the Filling
1 LB bag (about 3.5 C) frozen Oregon blackberries, thawed
1/2 Cup granulated sweetener of choice*
2 Tablespoons arrowroot powder or corn starch (not Paleo)
*(e.g. coconut palm sugar, maple sugar, organic cane sugar [not Paleo], xylitol)
Preheat oven to 350 degrees. Bake hazelnuts on a rimmed baking sheet for 8 minutes.
Let cool slightly, then rub them together to remove most of the skins.
Pulse hazelnuts in a food processor until they are mostly mealy with a few chunks.
Add almond floor, sweetener, and sea salt; pulse until combined.
Add chunks of butter or coconut oil and pulse until mixture is mostly combined and very crumbly, with a few small chunks of butter left.
Press crust into 9″ springform pan, about 1″ up the sides and smooth on the bottom. (Use a layer of plastic wrap and a metal measuring cup to flatten and shape into edges.) Chill 20 minutes.
Bake until golden but not totally baked through, about 15-20 minutes. Let cool 10 minutes.
Lifting from the corners, fold the corners of each square into the center, allowing the connected sides to hold the square shape of the pastry.
Squeeze excess moisture out of the blackberries in a mesh colander.
Toss thawed blackberries with sweetener and thickener; pour into tart shell.
Bake on a baking sheet (in case of drips) for 30 minutes. Berries will be bubbly and liquid. Chill for at least 30 minutes until berries firm up and you can cut slices.
Serve with vanilla ice cream or homemade whipped cream if you want and enjoy!