Step 1

Preheat oven to 300°. Toast hazelnuts on a rimmed baking sheet, tossing once, until golden brown, 20–25 minutes.

Step 2

Meanwhile, toast pumpkin seeds on a separate baking sheet, tossing once, until just beginning to brown in a few spots and very fragrant, 14–16 minutes.

Step 3

Let hazelnuts and pumpkin seeds cool. Purée in a food processor until a smooth paste forms (this will take several minutes and you will need to scrape down sides a few times.) Taste and season hazelnut–pumpkin seed butter with kosher salt.

Step 4

Finely grind blueberries, red pepper flakes, and a pinch of kosher salt in spice mill or with mortar and pestle. Drizzle toast with 2 Tbsp. oil and spread 2 Tbsp. hazelnut–pumpkin seed butter over each. Top with mango; drizzle with honey and oil. Sprinkle with blueberry–red pepper mixture and sea salt.