In a large pot, boil water and cook the pasta according to package directions.
Add oil to a large pan over medium-high heat. Cook the sausage just until it's browned, about 5 minutes. Then transfer sausage to a plate and set aside.
Drain excess oil except for 1 Tablespoon. Then add the onions and sauté for 1 minute. Then add the garlic and sauté for 1 minute.
Pour in the broth and add the flour and lemon juice.
Stir until the flour dissolves.
Add the sun-dried tomatoes and heavy cream. Cook for 2-3 minutes.
Return the sausage to the pan and cook with the other ingredients for 1-2 minutes, until the sauce thickens slightly.
Stir in the spinach and cook just until it has wilted, about 1-2 minutes.
Add the cooked pasta and stir to coat in the sauce.
Garnish with basil and serve.
Notes
Makes 4-5 servings. Make it dairy-free: use dairy-free whipping cream instead of heavy cream.