Preheat the oven to 200°F. (If making multiple omelets, keep the cooked omelets in the oven on a baking sheet until all are complete.)
In a medium bowl, whisk together eggs, salt, and black pepper.
In a non-stick pan, heat olive oil over medium heat. Sauté spinach until wilted, add in tomatoes and egg.
After egg mixture begins to set around edges, about 25 to 30 seconds, carefully lift the egg from the side using a heat-safe spatula, and tilt the skillet, so uncooked egg can reach the bottom of the pan. Repeat this process, tilting as necessary.
In a non-stick pan over medium heat, brown the chicken sausage on both sides. Toast the bread.
Add feta cheese and fold the omelet in half using the spatula. Portion onto the bread and serve with chicken sausage and raspberries.