Saute bacon in large pot over medium-high heat until crisp & browned. Using slotted spoon, transfer bacon to paper towels to drain. To the pot, add leeks, corn, potatoes, and jalapeno; saute 5 minutes until tender and fragrant. Add broth and Lactaid and simmer uncovered over medium heat until vegetables are tender, about 15 minutes. Using a ladel, very carefully transfer 3 cups soup to blender. Holding blender top firmly, puree until smooth. Return puree to soup in pot and season to taste with salt and pepper. Ladle chowder into bowls and garnish with bacon, red onion, and avocado.