I like to use a mixture of meat in mine, and like to have a good mushroom-based gravy/sauce. Here's my recipe. I adapted it to the smoker by putting the meat on a Q-Matz, and smoking at 250 in my MES until I got the IT called for in the recipe. If it isn't at temperature after three hours, I bring it inside and finish it in the oven. Three hours is plenty enough smoke.
Meatloaf with Mushroom Gravy
4 tablespoons unsalted butter
1 cup water
¼ oz. dried porcini mushrooms
16 square or 18 round saltines
10 oz. white mushrooms, trimmed
1 tablespoon vegetable oil
1 onion, chopped fine
4 garlic cloves, minced
1 pound ground pork
2 large eggs
1⅓ tablespoon Worcestershire
1 pound 85 percent lean ground beef
¾ teaspoon minced fresh thyme
¼ cup all-purpose flour
2½ cups low-sodium chicken broth
Heat oven to 375º.Microwave water & porcini mushrooms (1 minute). Sit until softened, (5 minutes). Remove porcini from bowl, mince & strain using coffee filter. Reserve ¾ cup.
Finely grind saltines in food processor. Transfer to bowl. Pulse half of white mushrooms in processor until finely ground, 8 to 10 pulses.
Brown onion in oil, 6-8 minutes. Add processed white mushrooms and ¼ teaspoon salt. Cook until liquid evaporates and mushrooms begin to brown, about 5 minutes. Add garlic. Cook until fragrant, about 30 seconds. Transfer to saltine bowl.
Combine beef, pork, eggs, 1 tablespoon Worcestershire, 1 teaspoon salt, ¾ teaspoon pepper, and ¼ cup reserved porcini liquid to cooled white mushroom– saltine mixture. Shape into 10x6" loaf in skillet. Bake to 160º, 45-55 minutes. Transfer to carving board. Tent with aluminum foil.
Thinly slice remaining white mushrooms. Keep 2 T. fat and heat until shimmering. Add sliced white mushrooms & porcini mushrooms and cook, stirring occasionally, until deep golden brown, 6-8 minutes. Stir in thyme and ¼ teaspoon salt., Cook until fragrant (30 seconds). Add flour and cook, stirring frequently, until golden, about 2 minutes. Slowly whisk in broth, ½ cup reserved porcini liquid, 1 teaspoon Worcestershire, scraping up any browned bits, and bring to boil. Reduce heat and simmer, whisking occasionally, until thickened, 10-15 minutes. Season with salt and pepper to taste. Slice meatloaf and serve with mushroom gravy.