Preheat oven to 350°. Coat 8x8” baking pan with vegetable oil spray; line with parchment, leaving overhang on all sides. Toast cashews, sesame seeds, and flaxseed in separate areas on a rimmed baking sheet, stirring occasionally (but not mixing), until golden brown, 10–12 minutes. Let cool. Set aside 2 Tbsp. sesame seeds and 1 Tbsp. flaxseed.
Process cashews and remaining seeds with quinoa bran, salt, cinnamon and cardamom in a food processor until mostly finely chopped. Place in a medium bowl.
Bring maple syrup and coconut oil to a boil in a small saucepan; cook, stirring, 2-3 minutes. Pour over cashew mixture and stir to coat.
Press mixture firmly into prepared pan with wet hands (it will be sticky). Top with reserved seeds; press to adhere. Bake until golden brown, 25–30 minutes. Let cool, then cut into bars.
Do Ahead: Bars can be made 2 weeks ahead. Store airtight at room temperature.