1. Heat a 12-inch skillet over medium heat and add the olive oil. "Spear" the garlic clove on the tines of a fork. When the oil is hot and begins to smoke lightly, add the almonds and toast in the oil, stirring with the fork, for 30 seconds or until lightly browned. By stirring the nuts with the garlic clove on the end of the fork, it imparts a garlic flavor without overwhelming the almonds.
2. Add as much spinach as can comfortably fit in the pan along with the salt and red pepper flakes. Add more spinach leaves as the spinach in the pan cooks and compresses; adding spinach in handfuls and stirring until all of the spinach is cooked. Sprinkle with lemon juice and Parmesan cheese. Serve immediately.