To make canned spaghetti sauce taste like homemade you can add some sauteed fresh aromatics like onions or garlic in olive oil or butter, then you can simmer the canned spaghetti sauce with some extra seasonings like basil, dried oregano or even a pinch of sugar/red pepper flakes and even a splash of wine or pasta water.
Then you can finish the canned spaghetti sauce with some Parmesan rind for richness or fresh herbs.
For meats in the spaghetti you can brown the meat and simmer it longer which also deepens the flavor of the spaghetti and spaghetti sauce.
Sauteed diced onions, garlic or even some celery and or carrots in some olive oil and butter before you add it to the spaghetti sauce also creates a fresh, fragrant base.
Adding some black pepper, and or fresh herbs like minced parsley on top can also help make the canned spaghetti sauce taste like homemade.
Italians also put butter in their pasta sauce, especially in Northern Italy where it's a staple for creamy sauces like sage for ravioli, or to finish dishes like risotto, but olive oil is what dominates Central and Southern Italy for tomato based sauces, although butter is used in some tomato sauces for richness and emulsification.
Regions of Italy like Emilia-Romagna and Lombardy use butter frequently for sauteing and enriching their sauces, like in dishes of burro e salvia "butter and sage" or for finishing risottos.
And famous recipes like Marcella Hazan's tomato sauce, incorporates butter for a balanced, sweet flavor in simple tomato sauce.
But in Central and Southern Italy, olive oil is the main and primary fat for most traditional dishes, especially with garlic, tomatoes, and herbs, which reflects the warmer climate where olives thrive.
When you add butter to pasta sauce, the butter makes the pasta sauce richer and smoother as well as glossier.
The butter added to the pasta sauce, makes the pasta sauce richer, smoother and glossier by emulsifying the liquids and fats, while also mellowing the acidity for a more balanced and luxurious flavor and silky texture which clings better to the pasta.
The butter in the pasta sauce also transforms the lower fat sauces like the tomato based sauces, by adding body and preventing them from becoming starchy or pasty.
The key affects of adding butter to pasta sauce are emulsification, gloss and sheen, acidity reduction, texture and creaminess and richness and flavor.
The butter binds the sauce and starchy pasta water together and helps the sauce cling to the pasta perfectly.
The butter in the pasta sauce also gives the finished pasta dish a beautiful and appealing gloss.
The fat in the butter, helps to soften the sharp and abrasive taste from the tomatoes or onions and rounds out the sauce.
Butter added to pasta sauce also creates a velvety, smooth consistency, which makes the pasta sauce feel more decadent as well.
And the butter in the pasta sauce adds a rich and delicate flavor and also enhances other tastes in the pasta sauce.
To add butter to your pasta sauce, cook the pasta until al dente and reserve a cup or two of starchy pasta water.
Then add the drained pasta directly to the sauce in it's pot and turn off the heat and stir in cold butter and a splash of pasta water.
Next toss the pasta in the buttered pasta sauce until the butter melts and emulsifies, which creates a cohesive glossy sauce that coats the noodles.