Place top oven rack in the center position and pre-heat oven to 350°F if you're cooking in a gas, electric, or propane oven. If you're cooking on a wood stove, bank your wood and place a meat thermometer inside the stove. You want a temperature of about 325 F when you add the crisp. I find the temperature still rises after that for a few minutes. 


Place blueberries in a large bowl.

Add maple syrup, cinnamon, allspice, rosemary, and salt. Toss to combine and set aside.


Combine the topping ingredients in a separate bowl and stir until oats are thoroughly coated and all ingredients are well combined. Set aside. 


Pour blueberry mixture into a 10” cast iron skillet and spread into an even layer.

Spread the topping evenly across the top in a uniform layer, as well. 


Place into pre-heated oven and bake for 30 minutes. If the top layer is nicely browned at this point, cover dish loosely with aluminum foil to prevent over-browning.

Bake for another 15-20 minutes or until the blueberry crisp is nice and bubbling.

Remove from oven and set aside to cool for 5-10 minutes. 


Serve warm with some vanilla ice cream whipped cream, or yogurt.