Preheat the oven to 350°F / 175°C.
Spray a 15x10-inch baking sheet with nonstick cooking spray. A 9x13-inch baking dish may also be used.
Slightly roll out the store-bought pie crust.
Place the pie crust into the prepared baking sheet or baking dish.
Trim any excess rounded edges with a sharp knife.
Press the trimmed pieces of dough into the corners of the pan to fill any uncovered areas.
In a large mixing bowl, beat the eggs until fully combined.
Add the half and half, Dijon mustard, salt, and black pepper.
Whisk until the egg mixture is smooth and evenly blended.
Sprinkle the cubed ham evenly over the unbaked pie crust.
Add the grated cheddar and Monterey Jack cheese blend.
Sprinkle the chopped sun-dried tomatoes and chopped green onions evenly over the crust.
Place the pan carefully onto the oven rack.
Pour the egg mixture evenly over the ham, cheese, sun-dried tomatoes, and green onions.
Bake for 45 to 50 minutes, or until the center of the quiche is puffed and slightly firm.
Remove the quiche from the oven and allow it to cool slightly before slicing.
Serve warm for breakfast or brunch.
To serve as an appetizer, refrigerate the quiche for at least 3 hours, then slice into small cubes or pieces.
Store leftovers in an airtight container in the refrigerator for up to 5 days.