In a medium bowl, whisk together 1.25 cups all-purpose flour and 1/4 tsp salt. Add 6 tbsp cold cubed unsalted butter. Using a pastry cutter or fingertips, cut the butter into the flour until mixture resembles coarse crumbs with pea-size bits of butter remaining.

Bring dough together

Sprinkle 2 tbsp ice water over the flour mixture and gently toss with a fork until the dough just begins to hold together. Add up to 1 more tablespoon water only if necessary. Do not overwork.

Chill and roll

Shape dough into a disk, wrap in plastic, and chill at least 30 minutes. On a lightly floured surface, roll dough to a 11-inch circle and fit into a 9-inch (23 cm) pie or quiche pan. Trim and crimp edges. Refrigerate while preparing filling.

Blind-bake (optional for crisp crust)

Preheat oven to 375°F (190°C). Line crust with parchment and fill with pie weights or dried beans. Bake 12 minutes, remove weights and parchment, then bake 6–8 minutes more until lightly golden. Remove and cool slightly. If you prefer a softer bottom, you may skip blind-bake and increase baking time for the filled quiche by about 10 minutes.

Filling

Preheat and prepare vegetables

Preheat oven to 375°F (190°C) if not already. In a small skillet, heat 1 tsp vegetable oil or butter over medium heat. Add 1/4 cup finely chopped onion and sauté 2–3 minutes until soft and translucent. Add 1 cup fresh corn kernels and sauté 3–4 minutes until corn is tender and beginning to brown. Remove from heat and let cool slightly.

Mix custard

In a medium bowl, whisk together 4 whole eggs and 1 cup half-and-half until smooth. Stir in 1 tsp salt, 1/2 tsp black pepper, and 1/4 tsp ground cumin.

Assemble filling

Combine the sautéed corn and onion with 1/2 cup diced roasted green chiles, 3/4 cup shredded pepper jack, 3/4 cup shredded sharp cheddar, and 2 tbsp chopped cilantro in a bowl. Spread the mixture evenly in the prepared pie crust.

Pour custard

Pour the egg and cream mixture over the corn-cheese mixture, gently pressing down any ingredients that float above the custard so filling is evenly distributed. Leave a small gap below the top of the crust to prevent overflow.

Bake

Place quiche on a baking sheet and bake in the 375°F (190°C) oven for 30–35 minutes, or until the center is set (a slight jiggle is okay) and the top is lightly golden. An instant-read thermometer inserted in the center should read about 165°F (74°C).

Rest

Remove quiche from oven and let rest on a wire rack 10–15 minutes to finish setting. This improves slices and texture.

Finish (optional)

Before serving, dollop sour cream (about 1/2 cup total) on top or serve on the side. Garnish with additional chopped cilantro (1 tbsp) and 1 tbsp thinly sliced green onion. Slice into 6–8 pieces and serve warm or at room temperature.