Preheat oven to 350°F (177°C).
Make crisp topping: Using a hand mixer or stand mixer, mix together butter, brown sugar, and vanilla until incorporated. Add oats, pecans, almond flour, cinnamon, and salt to the bowl and mix together with a spatula. Once the mixture begins sticking together use your hands to continue mixing until small clumps are formed.
Make blueberry filling: Add blueberries to an appropriately sized baking dish based on the amount of portions. In a small bowl, combine salt, corn starch, and brown sugar. Sprinkle the corn starch mixture over the top of the blueberries.
Assemble: Add the crisp topping in a layer over the blueberries.
Place the blueberry crisp in the oven and bake for 25-40 minutes or until the blueberries are bubbling in the center of the baking dish and the topping is beautifully crisp and golden. See note. Let cool down for 5 to 10 minutes before portioning.
Serve: Enjoy blueberry crisp with milk and a scoop of vanilla ice cream (if using).