Step 1: Sauté the Aromatics and Vegetables
Preheat your oven to 375°F (190°C). In a large skillet, heat the olive oil or butter over medium heat. Add the diced onion and celery, and sauté for 5-6 minutes until softened. Add the minced garlic and dried thyme, and cook for 30 seconds until fragrant. If using fresh broccoli, add it now and sauté for 2-3 minutes until it turns bright green. Remove from heat. (If using frozen, thawed broccoli, stir it in off the heat).

Step 2: Create the Honey Mustard Sauce
In a medium bowl, whisk together the mayonnaise, Dijon mustard, honey, whole grain mustard (if using), lemon juice, garlic powder, and onion powder until completely smooth and emulsified. Whisk in the chicken broth until you have a smooth, pourable sauce.

Step 3: Combine the Filling and Sauce
In a large mixing bowl, combine the cooked chicken and the sautéed vegetable mixture. Pour the honey mustard sauce over the top. Gently stir until the chicken and vegetables are evenly and thoroughly coated.

Step 4: Assemble the Bottom Layer
Lightly grease a 9×13 inch baking dish. Unroll one can of the crescent roll dough. If using perforated triangles, press the seams together firmly to create one solid rectangle. Press this sheet of dough evenly into the bottom of the prepared baking dish, stretching it slightly to fit if needed. This forms your bottom crust.

Step 5: Add the Filling and Cheese
Spread the saucy chicken and vegetable mixture evenly over the crescent dough base. Sprinkle the 1 cup of shredded cheese evenly over the chicken layer.

Step 6: Create the Top Crust
Unroll the second can of crescent dough. Again, press any seams together. Carefully place this sheet over the cheese layer, stretching it gently to cover the entire surface. Press the edges lightly to seal with the bottom layer if possible.

Step 7: The Golden-Brown Finish
Using a pastry brush, brush the entire top surface of the crescent dough with the beaten egg. This is essential for achieving a deep, glossy, golden-brown crust. Sprinkle the top with everything bagel seasoning or poppy seeds.

Step 8: Bake to Flaky Perfection
Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the top crust is puffed and a deep, rich golden brown, and the filling is bubbly around the edges.

Step 9: Rest, Garnish, and Serve
Remove the bake from the oven and let it rest for 10-15 minutes. This is crucial—it allows the cheesy, saucy filling to set slightly, making it much easier to cut and serve cleanly. Garnish with fresh parsley or chives. Use a sharp knife to slice into squares and serve warm