Warm olive oil in a large saucepan over medium heat. Add minced garlic and sauté for 1 minute. Slowly whisk in warmed half-and-half, zest and juice from 4 lemons, salt and pepper. Bring cream mixture to boil. Reduce heat to low and simmer for 15 to 20 minutes. Bring a large pot of salted water to boil and cook pasta until al dente, according to package label directions. Drain pasta and return to pot. Pour cream mixture on pasta and cook over medium-low heat, stirring, for 3 minutes. Cut asparagus into 1-inch pieces and steam in microwave; fold into pasta mixture with freshly grated Parmesan and halved cherry tomatoes. Cut 2 lemons in half, then into 1/4-inch slices. Remove seeds. Add lemon slices to pasta and toss until all ingredients are well combined. Serve hot.