Step 1

Preheat the oven to 375 degrees F.

Step 2

Cut off the very tops of the peppers. Remove and discard the ribs and seeds and set the peppers aside.

Step 3

Drain the tomatoes in a colander set over a medium bowl. Reserve the juice and set the tomatoes aside over a plate to catch any residual juices. Stir the couscous, oregano, 1 teaspoon salt and 1/2 teaspoon black pepper into the tomato juice and set aside while preparing the filling.

Step 4

Heat 1 tablespoon of the olive oil in a large skillet over medium-high heat. Stir in the onion, zucchini, half the garlic and 1/2 teaspoon salt and cook, stirring frequently, until the vegetables are softened and just beginning to brown, about 3 minutes. Increase the heat to high, stir in the couscous mixture and simmer rapidly, stirring frequently, until the couscous is just al dente and the liquid is beginning to thicken, about 5 minutes. Stir in the spinach and cook, adjusting the heat if necessary, until the leaves are bright green and just beginning to wilt, about 30 seconds. Set the filling aside to cool slightly.

Step 5

To make the sauce, combine the remaining garlic and olive oil in a Dutch oven, add the chile flakes if using and stir to combine. Place the pot over medium-high heat and cook, stirring occasionally at first then more frequently as the oil starts to sizzle to prevent the garlic from burning, until the garlic starts to stick to the edge of the spoon and is just beginning to turn a very pale straw color, 2 to 3 minutes. Stir in the reserved drained tomatoes plus any accumulated juices, 1 cup water, 1/2 teaspoon salt and 1/2 teaspoon black pepper and cook, stirring frequently, until the mixture just begins to come together and thicken, about 3 minutes. Remove from the heat.

Step 6

Fold the feta and basil into the couscous filling. Fill a pepper with about 3/4 cup of the filling, scooping it in loosely and shaking the pepper to level the filling rather than packing it down. Nestle the filled pepper in the sauce in the pot, then repeat with the remaining peppers, propping them up against each other and the sides of the pot for stability during baking.

Step 7

Cover the pot and bake until the peppers are tender but not mushy and the sauce is bubbling, 45 to 60 minutes. Check after 45 minutes to see if the peppers are tender but not soft or they will be overcooked and mushy. Let rest for at least 15 minutes before serving. Serve hot, warm or at room temperature with a generous scoop of the tomato sauce.