Spaghetti with Tomato-Mushroom Butter and a Secret Ketchup Glaze

Bring a large pot of generously salted water to a vigorous boil. Slice the mushrooms, dice the onion, mince the garlic, and crush the tomatoes by hand into a bowl — juices and all.

In a small saucepan over medium-low heat, melt 1 tablespoon butter with the ketchup. Stir constantly until the mixture darkens slightly and coats the back of a spoon, about 3 minutes. Remove from heat and set aside — this is your secret weapon.

In a wide skillet over medium-high heat, melt half the butter with the olive oil until foaming. Add the mushrooms in a single layer and cook undisturbed for 3 minutes until golden beneath, then toss and cook 2 minutes more. Season with a pinch of salt.

Push mushrooms to the edges and add the diced onion to the center. Cook until softened and translucent, about 4 minutes, then add the garlic and cook 30 seconds until fragrant.

Pour in the crushed tomatoes with their juices. Season with salt and black pepper. Simmer vigorously for 5 minutes, letting the tomatoes break down into a glossy sauce. The mixture should look thick and seductive.

Reduce heat to low. Add the remaining butter in pieces, swirling the pan until it melts into the sauce and creates a silky emulsion. This is the butter — don't skimp, don't substitute.

Cook the spaghetti in the boiling salted water until 2 minutes shy of al dente. Reserve 1½ cups of the starchy pasta water before draining.

Add the drained spaghetti directly into the skillet with the tomato-mushroom butter. Pour in a splash of pasta water and toss vigorously over medium heat for 90 seconds, letting the pasta drink up the sauce and develop a glossy coating.

Divide the pasta among warm bowls, twirling into nests.

Drizzle the reserved ketchup glaze in a dramatic zigzag across each portion — your guests don't need to know, but the sweet-tangy depth will have them asking for your secret.

Shower generously with grated cheddar and scatter parsley over the top. Serve immediately while the butter still glistens.