Make Pesto: Add olive oil and garlic cloves to a small saucepan and cook over medium-low heat for 4 minutes or until garlic is very fragrant and beginning to brown. Let oil and garlic cool for 5 minutes and then add to food processor. Add remaining pesto ingredients and process until desired consistency.
Cook pasta according to package instructions. Add frozen peas during the last 2 minutes. Drain.
In a large skillet, heat up 1 TBSP olive oil and add chicken sausage. Cook 3-4 minutes or until it begins to brown, toss occassionally.
Add leeks to skillet and cook for 3-4 minutes.
Add pasta and peas to the skillet and gently fold in serrano pepper pesto. Garnish with basil leaves and serve hot.