Preheat the oven to 450°F.
Wash the broccoli crowns thoroughly.
Cut the broccoli into bite-sized florets.
Dry the broccoli well to help it roast properly.
In a large mixing bowl, combine the olive oil, lemon zest, lemon juice, salt, black pepper, red pepper flakes, dry ranch seasoning, and minced garlic.
Whisk until the mixture is fully blended.
Add the broccoli florets to the bowl.
Toss until the broccoli is evenly coated with the seasoning mixture.
Spread the coated broccoli in a single layer on a large rimmed baking sheet.
Bake for 10 to 12 minutes.
Remove the baking sheet from the oven.
Turn the broccoli pieces over carefully.
Sprinkle the sliced almonds evenly over the baking sheet.
Return the baking sheet to the oven.
Bake for an additional 5 to 10 minutes, or until the broccoli reaches the desired tenderness and the almonds are lightly toasted.
Monitor the almonds closely, as they can brown quickly.
Remove the broccoli from the oven.
Sprinkle the hot broccoli evenly with grated parmesan cheese.
Serve warm.