Preheat the oven to 325°F (165°C). Line a large rimmed baking sheet with parchment paper to prevent sticking and make cleanup easy.

In a large bowl, whisk together the olive oil, lemon juice, lemon zest, lemon pepper seasoning, garlic powder, kosher salt, black pepper, and red pepper flakes (if using) until you have a loose, fragrant paste.

Add the raw almonds to the bowl and stir well with a spatula or wooden spoon, scraping the bottom of the bowl so every almond is evenly coated with the seasoning mixture.

Pour the seasoned almonds onto the prepared baking sheet and spread them into a single, even layer, avoiding piles so the nuts roast rather than steam.

Place the baking sheet on the center rack and roast for 14–18 minutes, stirring once around the 8-minute mark. The almonds are done when they smell toasty, look slightly darker, and you hear a faint crackle. They will crisp further as they cool.

Remove the pan from the oven and let the almonds sit for 3–4 minutes. Carefully taste one and adjust the seasoning if desired by sprinkling a little extra lemon pepper over the warm nuts and tossing on the tray.

Let the almonds cool completely on the baking sheet at room temperature, 20–30 minutes, until fully cooled and crisp. Break up any clusters with your fingers.

Transfer the lemon pepper almonds to a serving bowl, or store in an airtight container or jar. Serve as a snack on their own or on a board with cheese, olives, and fresh fruit.