Cut and Season Tomatoes: Halve the grape tomatoes and place them in a large mixing bowl. Add the diced yellow onions, 2 tablespoons olive oil, and 1 tablespoon pesto mix to the tomatoes. Toss until the tomatoes and onions are evenly coated.
Fill Baking Dish: Pour the tomato mixture into a 9-by-13-inch baking dish. Spread it into an even layer.
Make Cheese Crumble: In a small mixing bowl, combine the softened butter and flour until the mixture looks crumbly. Add the Parmesan cheese and Pecorino Romano cheese, then mix again until everything forms coarse crumbs.
Top and Bake Tomatoes: Sprinkle the cheese crumble evenly over the tomato mixture. Bake at 425°F for about 15 minutes, until the tomatoes begin to soften and the topping starts to turn lightly golden.
Make Almond Pesto Topping: Add the sliced almonds and 2 tablespoons pesto mix to a food processor. Pulse until the almonds are finely chopped and the mixture looks crumbly.
Add Fish: Remove the baking dish from the oven. Place the tilapia fillets over the baked tomato mixture in a single layer.
Brush With Egg: Brush the tops of the tilapia fillets with the beaten egg so the almond topping will stick.
Add Almond Topping: Sprinkle the almond pesto topping evenly over the fish. Press it on gently with your fingers or the back of a spoon.
Bake Fish: Return the baking dish to the oven and bake at 425°F for 12 to 15 minutes, until the fish flakes easily with a fork and the almond topping is lightly toasted.
Cut Oranges: Peel the oranges and cut them into chunky segments.
Make Spiced Orange Mix: In a mixing bowl, stir together 2 tablespoons olive oil, ground allspice, and kosher salt. Toss gently until the oranges are coated.
Dress Arugula: Place the baby arugula in a large mixing bowl. Add the brown sugar balsamic dressing and toss with tongs until lightly coated.
Plate Salad: Transfer the dressed arugula to a serving platter. Arrange the spiced orange segments over the top.
Add Goat Cheese: Sprinkle the crumbled goat cheese over the orange salad.
Finish and Serve: Serve the baked fish and tomatoes with lemon wedges. Squeeze fresh lemon juice over the fish right before eating.