Boil the noodles: Cook the spaghetti or lo mein noodles in well-salted boiling water until just shy of al dente, about 1 minute less than the package directions. Reserve 1 cup of the starchy pasta water before draining.

Mince the garlic: While the water heats, mince the garlic very fine by hand or with a garlic press. Fine, even pieces cook evenly and turn golden instead of burning in spots.

Mix the sauce: In a small bowl, stir together the soy sauce, oyster sauce, brown sugar, and white pepper until the sugar dissolves. Set this sauce aside near the stove.

Melt butter and oil: In a large skillet over medium-low heat, melt the butter with the vegetable oil until it foams gently. The oil helps keep the butter from browning too fast.

Cook garlic low and slow: Add the minced garlic and cook over medium-low heat, stirring constantly, for 2 to 3 minutes until it turns pale gold and smells toasty. Watch closely, since garlic can go from golden to burnt in seconds.

Add the sauce: Pour the soy sauce mixture into the skillet with the garlic and let it bubble for about 30 seconds, until slightly thickened and fragrant. Lower the heat if it starts to spatter.

Toss in the noodles: Add the drained noodles directly to the skillet and toss with tongs until every strand is coated in the glossy garlic sauce. This takes about 1 to 2 minutes over medium-low heat.

Loosen with pasta water: If the noodles look dry or clumpy, add 2 to 3 tablespoons of the reserved pasta water and toss again until the sauce turns silky and clings evenly.

Garnish and serve: Remove the skillet from the heat and stir in the sliced green onions and parmesan, if using. Serve the garlic noodles immediately while hot and glossy.