Step 1

Preheat oven to 350°F. In a small pot over medium heat, bring oil and red-pepper flakes to a simmer, then remove from heat. Swirl in cinnamon and let stand a few minutes (the longer it sits, the spicier it will be). Strain into a large bowl though a fine-mesh sieve; remove 1 tablespoon or so of spicy oil and set aside.

Step 2

To that same large bowl with spicy oil, add oats, buckwheat, seeds, almonds, maple syrup, kosher salt, and egg whites. Combine with a wooden spoon until everything is mixed and moistened. Transfer to a parchment-lined rimmed baking sheet and bake, rotating and mixing every 15 minutes, until golden brown and fragrant, 25 to 30 minutes.

Step 3

Arrange citrus on your plate or plates. Scatter with a handful of granola and top with a spoonful of yogurt (use the back of a spoon to give it a nice swoop), if desired. Drizzle with reserved spicy oil and sprinkle with flaky salt. Save any remaining granola in an airtight container up to 3 weeks.