Preheat oven to 350°F (175°C). Line baking sheets with silicone liners or parchment paper.
Whisk together the flour, baking powder, and salt. Stir in the oats. Set aside.
Using an electric mixer on medium speed, beat the butter and brown sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the vanilla.
Reduce mixer speed to low. Add the flour mixture in 3 or 4 portions, mixing just until combined. Stir in the blueberries, white chocolate, and almonds.
Drop the dough in 3 tablespoon portions (a cookie scoop works well) onto prepared pans. Leave about 2 & 1/2 inches between cookies. Flatten the tops of the cookies slightly.
Bake, one pan at a time, 18-22 minutes. The edges should be browned and the centers set. Cool on the pans on wire racks for 5 minutes. Then, transfer the cookies to wire racks to cool completely.
Notes
Store in an airtight container at room temperature up to 5 days.