Preheat oven to 400 degrees F and position oven rack in the upper third position. You will need a ceramic or glass baking dish measuring approximately 9- to 10- inches or equivalent.
Heat a large skillet over medium-high heat. Add the olive oil and the onion to the skillet and sauté for approximately 5 minutes, stirring frequently. Stir in the garlic and sauté for an additional minute more before adding the tomatoes, and their juices, to the skillet. Bring to a simmer, then reduce heat to low, and continue to simmer until thick chunky sauce is formed, stir frequently to prevent burning. Season with salt and pepper, to taste.
Transfer sauce to baking dish. Add the drained, cooked beans, gently tossing them to coat in sauce. Crumble big chunks of feta over the top of the beans and sauce and gently press into the sauce. Drizzle with olive oil and a pinch of salt.
Bake for approximately 30 minutes, or until sauce is bubbling and cheese is beginning to brown on the top.