Pour 4 quarts of water into a 6-quart stock pot and add 1 tablespoon kosher salt; cover and heat on high until the water reaches a rolling boil.
Preheat the oven broiler.
In a large skillet over medium heat, warm 2 tablespoons vegetable oil.
Add the ground beef to the hot skillet, break it into small pieces, season with 1 teaspoon kosher salt, and cook over medium to medium-high heat until no longer pink, stirring and breaking up the meat frequently.
Pour the 24-ounce jar of Ragu sauce into the skillet with the browned beef, stir to combine, then add 2 teaspoons garlic powder, 1 teaspoon onion powder, and 1 teaspoon black pepper. Reduce heat to low and keep warm while the pasta cooks.
Arrange the bread slices on a baking sheet and top each slice with a pat of butter; sprinkle each with 1 teaspoon garlic powder and 1/2 teaspoon kosher salt (divided across slices). Set aside.
When the water is at a rolling boil, add the spaghetti noodles and gently press them under the water with a wooden spoon until submerged; leave the lid slightly ajar to prevent boiling over and reduce heat to medium once the boil returns.
Stir the noodles frequently and cook for 9–10 minutes or according to package directions until al dente.
When the noodles have about 3 minutes left, place the prepared bread under the broiler and watch closely; remove when the bread is toasty and the butter has melted.
Drain the cooked pasta in a colander, return it to the pot, and plate with the warmed beef and Ragu sauce. Serve immediately with the garlic toast.