Bake potatoes in microwave on high for approximately 12 minutes or in oven at 350 degrees for 1 to 1 1/2 hours or until done. Set potatoes aside.
In large pot cook bacon over medium/medium-high heat until done. Remove, drain, and set aside.
Toss chopped onion into bacon droppings and saute 2-3 minutes.
Add frozen corn and enough milk to allow corn to simmer. Add salt, garlic, pepper, and cayenne to taste, cover and allow to simmer over medium heat until corn is tender, about 5 minutes. I use frozen corn in winter months and for simplicity; however, if fresh corn is available, scrape kernels from 5 large ears with dull side of a butter knife and simmer until tender.
Add remaining milk and cream. While it begins to warm, remove skin from potatoes and cut potatoes into chunks, add to pot and continue simmering.
Remove shells from shrimp and add. Simmer for approximately 5 minutes or until pink. Add more garlic, pepper, and cayenne to taste. Sometimes I will add a few generous dashes of Old Bay season as well.
Wash greens, drain, and chop into large pieces. Add greens to chowder, stir in well. Continue to simmer until greens are cooked down, about 5 minutes. Reduce heat to low.
Crumble bacon and stir in or use to top each serving.