After a record-breaking warm March and April, you'd expect this month to continue the heat wave trend. But thanks to a weakened polar vortex, this May could be America's second coolest in 15 years, with 141 million people across the Midwest and Northeast experiencing significantly chillier-than-normal temperatures. The dramatic shift has our meteorologists calling it one of the most significant seasonal reversals in recent memory.

Recipe-wise, this unexpected cool snap might have you trading in your usual late-spring salads and grilled fare for something more substantial. When the thermometer drops and you're still reaching for that sweater, but still want to celebrate the season's freshest ingredients, try this asparagus and leek gratin. It's a dish that will transform abundant spring vegetables into something rich, warming and utterly satisfying, perfect for the surprisingly chilly May evenings ahead of us when you still want to enjoy dinner on the patio, but need just the right dish to feel perfect while doing so.

Asparagus and Leek Gratin

Serves 6-8

Ingredients:

2 lbs fresh asparagus, trimmed and cut into 2-inch pieces

3 large leeks, white and light green parts only, sliced into half-moons

3 tablespoons butter

3 tablespoons all-purpose flour

2 cups whole milk, warmed

1 cup heavy cream

1½ cups Gruyère cheese, grated

½ cup Parmesan cheese, grated

¼ cup fresh chives, chopped

2 tablespoons fresh thyme leaves

Salt, pepper, and nutmeg to taste

½ cup panko breadcrumbs

2 tablespoons olive oil

Instructions:

Preheat oven to 375°F. Butter a 9x13-inch baking dish.

Blanch asparagus in salted boiling water for 3 minutes until bright green and crisp-tender. Drain and set aside.

In a large skillet, sauté leeks in 1 tablespoon butter until softened, about 8 minutes. Season with salt and pepper.

In a saucepan, melt remaining butter and whisk in flour. Cook for 2 minutes, then gradually add warm milk and cream, whisking constantly until smooth and thickened, about 5 minutes.

Remove from heat and stir in 1 cup Gruyère, Parmesan, chives, and thyme. Season with salt, pepper, and a pinch of nutmeg.

Layer half the asparagus and leeks in the prepared dish, pour over half the sauce. Repeat layers.

Top with remaining Gruyère. Mix panko with olive oil and sprinkle over top.

Bake 25-30 minutes until bubbly and golden. Let rest 10 minutes before serving.