Heat some oil in a large skillet over medium-high heat.
Season salmon and shrimp with salt and pepper on both sides.
Cook the salmon for 3-4 minutes on each side skin side down.
Remove the salmon from the skillet and remove any excess oil leaving about 2 tbsp in the skillet and reduce the heat to low.
Add the onions and cook for 2-3 minutes or until translucent.
Stir in the fresh garlic and red crushed pepper, cook for 20 seconds.
Increase the heat to medium-high. Add the white wine and reduce by half. This should take about 3-4 minutes.
Add the heavy cream, parmesan cheese, and season with salt and pepper.
Place the salmon back in the skillet along with the shrimp and spinach.
Cover and simmer for 7-10 minutes or until the sauce is thickened and the shrimp and salmon are completely cooked.
Serve immediately and enjoy!