1-First Step: Mise en place (5 minutes) Start by prepping all ingredients to avoid scrambling later. Dice 1 onion into 1/2-inch pieces for even cooking. Mince 3 garlic cloves finely, as large chunks burn easily. Slice 8 oz cremini mushrooms into 1/4-inch pieces to ensure they brown uniformly. Measure 28 oz crushed tomatoes, 1 tsp dried oregano, salt, and pepper. Chop fresh basil and grate optional Parmesan. Boil water in a large pot for the 8 oz spaghetti. This setup prevents overcooking and lets you focus on flavors.

2-Second Step: Cook the spaghetti (10 minutes) Bring a large pot of salted water to a rolling boil over high heat. Add 8 oz spaghetti and cook until al dente, about 10 minutes, stirring occasionally. Taste a strand at 8 minutes; it should have a slight bite. Reserve 1/4 cup pasta water before draining. This starchy water thickens the sauce later. Rinse? No, keep it warm in the colander covered with a lid. Al dente pasta holds up better in the mushroom sauce for spaghetti.

3-Third Step: Saute aromatics (3 minutes) While pasta boils, heat 2 tbsp olive oil in a large skillet over medium heat until it shimmers. Add diced onion and minced garlic. Cook for 3 minutes, stirring often, until soft and translucent but not browned. Low and slow here prevents bitterness. The aroma fills your kitchen, signaling good things ahead. If onions stick, add a splash of water.

4-Fourth Step: Brown the mushrooms (5-7 minutes) Add sliced cremini mushrooms to the skillet in an even layer. Cook undisturbed for 2 minutes, then stir for 5-7 minutes total until golden and water evaporates. Mushrooms release moisture first, then caramelize for nutty depth. Don’t crowd the pan; cook in batches if needed. This step defines the mushroom sauce recipe’s richness. Season lightly with salt to draw out more liquid.

5-Fifth Step: Simmer the tomato mushroom sauce (10 minutes) Stir in 28 oz crushed tomatoes, 1 tsp dried oregano, salt, and pepper. Bring to a gentle simmer over medium-low heat. Let it bubble for 10 minutes, stirring occasionally, until thickened. Tomatoes break down, melding with mushrooms for a cohesive tomato mushroom sauce. Taste and adjust seasoning; add a pinch of sugar if too acidic. This low simmer concentrates flavors without scorching.

6-Sixth Step: Combine pasta and sauce Add drained spaghetti directly to the skillet. Toss vigorously for 1-2 minutes to coat evenly. If dry, drizzle in reserved pasta water 1 tbsp at a time. The starch emulsifies into a silky pasta sauce. Heat through; mushrooms should stay tender, not mushy.

7-Final Step: Finishing touches and serving Remove from heat. Stir in chopped fresh basil for brightness. Divide into bowls, top with grated Parmesan if using. Serve hot with crusty bread. Garnish with extra basil leaves. For a family-style presentation, keep in the skillet. Pairs well with a green salad. Enjoy your tomato mushroom spaghetti recipe!