Make the hominy puree: In a saucepan over medium high heat simmer hominy and milk until warm. With a potato smasher or using a blender mash or puree hominy until smooth. Reduce heat to low stir in salt, pepper and butter. Taste and adjust seasoning; keep warm.
Make the shrimp: Heat oil in a large nonstick skillet over medium heat. Add sliced onion and sauté until tender and translucent, about 4 minutes.
Add garlic, cumin, salt and pepper and cook an additional 2 minutes.
Add shrimp, stirring frequently and cook until shrimp are pink, about 3 minutes.
Reduce heat add diced chipotles and tomatoes and simmer for 5 minutes until sauce thickens a bit. Serve warm over pureed hominy.