Put the garlic, anchovies, and capers in the work bowl of a food processor and pulse until finely chopped. Add the arugula, cheese, lemon juice, and olive oil, and pulse until the mixture is completely combined and is the consistency of a classic pesto. Add salt and pepper, to taste. To serve, spread on bread or crackers, or toss with pasta. Transfer any remaining pesto to a freezer-safe airtight container and freeze for up to 1 month.