Preheat the oven to 350°F and lightly grease a 9-inch tart pan with a removable bottom. Set aside.
Add blueberries, maple syrup, and tapioca starch to a medium bowl and toss until coated. Set the blueberries aside while you make the crust.
Add the almond flour, oats, maple syrup, baking powder, and salt to a different bowl and whisk until combined. Add the coconut oil and use your fingers to work it in until coarse crumbs form and the mixture holds together when pressed.
Remove a heaping ½ cup of the crumbs for the topping and pour the remaining crumbs into the prepared tart pan. Press the dough evenly into the pan. Pour the blueberries over the crust, making sure the juices stay behind in the bottom of the bowl.
Add the chopped pecans to the remaining crumble and sprinkle evenly over the top of the berries.
Bake for 40-45 minutes or until the filling is bubbling and the crust is lightly brown. At around 20 minutes, tent the tart with foil to prevent it from getting too brown. Let cool completely before slicing into wedges and serving.
Store leftovers in the refrigerator.
