In a large mixing bowl, add blueberries and all the filling ingredients; lemon juice, maple syrup, vanilla extract, arrowroot flour, and pink sea salt. Stir all ingredients well making sure the blueberries are well coated and mixed in with the other ingredients. Set aside.
In a separate large mixing bowl, toss all the ingredients for the oat crisp; rolled oats, blanched almond flour, coconut sugar, maple syrup, vanilla extract, cinnamon, and pink sea salt. Cube the cold butter and add it to the dry ingredients. Use a dough blender to work the butter into the mixture. Use your fingertips to finish working the butter and press into the dry ingredients until well dispersed and it starts to resemble crumbs.
To assemble your crisp, pour blueberry filling (and all accumulated juices) into a 9x9 inch baking dish or pan. Spread it out into an even layer. Sprinkle the oat mixture over the blueberries. Make sure you don't press down into the blueberries.
Place pan in the center of the oven and bake for 45 minutes. The topping should be golden brown and the edges and center of the blueberries should be bubbling. Allow the crisp to cool for about 10 minutes on a cooling rack. Serve warm with a scoop of vanilla ice cream or whipped cream. Enjoy!