To make corn chowder:

1. Adjust oven rack 6 inches from broiler element and heat broiler. Line a baking sheet with aluminum foil. Arrange poblanos cut side down, flush against short side of sheet. Spread corn in even layer on remaining portion of sheet next to poblanos.
2. Drizzle with 1 1/2 teaspoons olive oil. (Or spray with an olive oil spray.) Sprinkle with 1/4 teaspoon salt.
3. Broil until poblanos are mostly blackened and corn is well browned andtender, 10 to 15 minutes, flipping poblanos and stirring corn halfway through broiling.
4. Place poblanos in bowl, cover with plastic wrap, and let cool for 5 minutes. Remove skins and cut poblanos into ½-inch pieces; transfer to clean bowl and set aside.
5. Add remaining 1 1/2 teaspoons of oil to a Dutch oven or large pot. Add onion and ¼ teaspoon salt and cook until onion is softened and beginning to brown, 5 to 7 minutes. Add garlic and cook until fragrant, about 30 seconds.
6. Add broth, potatoes, roasted corn and poblanos to pot and bring to simmer. Cook at vigorous simmer until potatoes are tender, 15 to 20 minutes. 
7. Remove from heat and stir in milk.
8. Add torn pieces of corn tortilla and 2 cups of soup to a blender and blend for 1 minute until smooth.
9. Add the blended mixture back to the pot of soup and stir until combined.
10. Top with cilantro, red onion, and toasted tortilla chips. (Instructions for tortilla chips below)

To make tortilla chips:

1. Stack 4 corn tortillas together.
2. Cut into 1/2 inch squares.
3. Toss with olive oil or spread onto a parchment paper lined baking sheet and spray with olive oil.
4. Sprinkle with salt, then broil for 2-3 minutes, stirring frequently to ensure even browning. Keep a close eye on the chips so they don’t burn!