Take 1/2 onion and 3 cloves of garlic and pulse until smooth in food processor. Saute on med-high heat in cast-iron skillet with 1/2 tsp of olive oil (preferably Spanish) and 2 tbsp butter until just browning, then whisk in 2 cup room temp heavy cream. Whisk until just turning thick, then blend in 1/2 cup of grated Parmesan (Preferably Reggiano) and whisk until smooth. Drop to low heat and chiffonade a pound of freshly washed baby spinach. Saute the spinach in separate pan, until wilted, then incorporate spinach into sauce. Heat on medium heat until boiling, then remove from heat. Serve hot.