Bring a large pot of salted water to a boil. Cook the spaghetti according to the package instructions, then drain.
Meanwhile, heat your largest skillet over medium heat. Add 1 tablespoon of butter and 1 tablespoon of oil to the skillet. Sauté the mushrooms until they are soft and brown, about 10 minutes. Remove the mushrooms from the skillet.
Butterfly and separate chicken breasts. (To skip this step you can buy chicken "cutlets" at the store, which are thinner slices of chicken breast.) Salt and pepper both sides of each piece of chicken, then dredge in flour.
Add 2 tablespoons of butter and 2 tablespoons of oil to the skillet. Wait until butter is melted, then add the chicken to the skillet. Sauté the chicken 1-2 minutes per side. Add the wine and garlic. Cook the chicken in the wine for another 3 minutes.
Remove the chicken from skillet and tightly cover with foil to keep it warm. Add the mushrooms and 3 cups of marinara to the skillet and simmer for 10 minutes, stirring regularly.
To plate, place a heaping pile of spaghetti on each plate and top with 2 chicken cutlets and the mushrooms sauce. Garnish with fresh herbs.
Keep leftovers in an airtight container in the fridge for up to 3 days. The chicken and sauce leftovers keep well in the freezer for up to 3 months, but I recommend serving with fresh pasta.