Toss blueberries with 2 Tbsp lemon juice and 1 tsp lemon zest and set aside.

In a small bowl, whisk together ¼ cup sugar, 3 Tbsp flour and 1 tsp ground cinnamon and toss with the blueberries just until evenly coated. Pour into a 9 x 13– inch baking dish.

In a food processor fitted with a steel blade, combine 1 cup flour, ¼ cup granulated sugar, ⅓ cup brown sugar, and ⅛ tsp of salt. Pulse several times to combine. Add the diced cold butter and pulse until the butter is the size of peas.

Transfer the mixture to a bowl, add ½ cup oatmeal and use your hands to make large crumbles. Add ½ cup of the sliced almonds and mix to combine.

Spread the topping over the fruit and cover evenly, then sprinkle ½ cup of almonds over the top. Bake 40 minutes at 350˚F. The blueberries should be bubbling at the edges and the topping and almonds should be golden brown. Here's the hard part: let the crumble sit for at least 15 minutes before serving (it will thicken slightly as it cools). This will stay warm for a couple hours. It reheats beautifully the next day.