Cook bacon in a large skillet over medium heat until crisp. Transfer to a paper towel–lined plate and reserve 1 tbsp drippings in the pan.
Melt butter in the skillet. Sauté onion and jalapeño until softened, 4–5 minutes. Stir in garlic and cook 30 seconds.
Sprinkle flour over the vegetables and cook, stirring, for 1 minute to remove the raw taste.
Whisk in heavy cream and milk until smooth. Simmer gently, stirring, until slightly thickened, about 3–4 minutes.
Add cream cheese and stir until fully melted and the sauce is silky.
Fold in the corn and cook, stirring occasionally, until hot and creamy, 5–7 minutes.
Season with salt, pepper, and sugar if using. Adjust to taste.
Stir in cheddar just until melted, then remove from heat. Top with bacon and green onions and serve warm.