Preheat the oven to 350 degrees F (175 degrees C).
Place broccoli florets in a bowl. Add 1 1/2 teaspoons olive oil oil and 1/2 teaspoon of lemon pepper seasoning. Toss to coat and arrange in a single layer on a baking sheet. Place 1/2 of the lemon slices over the top of the broccoli.
Bake in the preheated oven for 15 minutes.
Meanwhile place asparagus in the bowl. Add remaining 1 1/2 teaspoons of olive oil and 1/2 teaspoon of lemon pepper. Toss to coat.
Add asparagus to the baking sheet in a single layer and place remaining lemon slices over the top of the asparagus. Cook for 10 minutes. Remove baking sheet from the oven and toss broccoli and asparagus together. Serve immediately.