*Classic Marinara Sauce: Heat oil in a large pot or Dutch oven over medium heat. Add onions; cook 10 to 12 minutes, stirring occasionally, until softened. Add garlic, red pepper flakes, and basil; cook 3 minutes, stirring occasionally.

Add tomatoes and use clean hands to break apart. Season mixture with salt and pepper to taste, and bring to a simmer. Reduce heat to low and gently simmer, covered, for 1 hour, until sauce thickens, stirring occasionally and continuing to crush tomatoes with a wooden spoon on the side of the pot. At this point, either remove sauce from heat and let cool completely before refrigerating overnight, or begin making poached eggs.

*Moroccan Marinara-Poached Eggs: Heat oil in a large skillet fitted with a lid over medium heat. Add fennel, 1/4 tsp. of the salt, and pepper; cook 4 to 5 minutes, until softened. Stir in Classic Marinara Sauce and harissa; bring mixture to a simmer.

One at a time, crack eggs into a ramekin, and slip into tomato sauce. Season eggs evenly with remaining 1/4 tsp. salt. Cover skillet and cook, simmering gently and reducing heat if necessary, until whites of eggs are set and yolks are still jammy, about 7 to 10 minutes. Sprinkle with feta and add dollops of yogurt. Garnish with reserved fennel fronds and a drizzle of olive oil, if desired. Serve with crusty bread.