| 1 Pie Crust |
| 1 Tbsp. Dijon Mustard |
| 2 Tbsp. Butter divided |
| 2 Medium Onions sliced lengthwise |
| Sprigs of Fresh Thyme |
| 4 Oz. Chanterelle Mushrooms sliced lengthwise |
| 2 Eggs |
| 1Cup Half-and-Half |
| 1 Cup Shredded Gruyere Cheese |
| 1Tsp. Sea Salt |
| Freshly Ground Black Pepper |
Preheat oven to 350° F. Roll out pie crust to fit in a 12-inch tart pan. Place in pan and press into the sides. Coat surface with mustard. Bake 10 minutes. Let Cool.
To prepare filling, melt 1 tablespoon butter in a deep skillet over medium heat. Add onions and saute 15 minutes. Add salt, pepper, and thyme leaves. Scrape into a small bowl. In the same skillet, melt remaining butter. Add mushrooms and cook 10 minutes. Remove from heat.
Combine eggs and half-and-half and beat until well blended. Sprinkle about half the cheese on the bottom of the tart shell. Spoon in onions. Pour in egg mixture. Place mushrooms all over the top, along with remaining cheese. Bake 40 minutes, or until tart is golden brown and filling is set. Serve warm or room temperature.