Blanch organic tomatoes in boiling water, then remove skin and seeds. Roughly chop and set aside.
In a large sauté pot, heat oil and sauté garlic and shallots until translucent. Add reserved fresh tomatoes and canned tomatoes.
Bring marinara to a simmer and cook for 30 minutes over low heat. Remove from heat, season with salt and pepper, then stir in parsley and basil.
While marinara simmers, combine half-and-half and cream in a large pot. Bring to a boil, watching carefully to prevent overflow.
Add grits, garlic, and salt to the cream mixture. Reduce heat and cook slowly for 45 minutes, stirring frequently and scraping bottom of pan.
When grits are tender and liquid is absorbed, stir in shredded cheese until combined.
In a sauté pan over medium-high heat, heat oil and cook shrimp until translucent. Season with salt and pepper.
Reduce heat to medium, add sausage and cook for 1 minute. Add marinara sauce and cook for 3 minutes.
Place 1/2 cup cooked grits in individual bowls. Divide shrimp and marinara between plates beside grits.
Drizzle basil oil over shrimp and top with chopped chives.