Preheat oven to 375 degrees.
Combine all Blueberry Filling ingredients in a large bowl. Stir gently to combine then spoon into a 9-inch baking dish.
Add all ingredients for the Almond Oat Topping to a medium bowl. Cut in butter with two knives until mixture is crumbly and butter is reduced to pea-size.
Sprinkle topping over Blueberry Filling in an even layer
Bake for 40 to 45 minutes or until topping is golden brown and blueberries are bubbly hot.*Note, check on the crisp after the first 30 minutes of baking. If sliced almonds are getting too brown, tent with aluminum foil. Remove crisp from oven and allow it to sit undisturbed for 10 minutes to allow juices to thicken.
Cover and store leftovers in the refrigerator up to 3 days.