Preheat oven to 300 degrees. Toss grape tomatoes in 1 Tbsp. olive oil and season with salt and pepper. Spread tomatoes out in a single layer on a baking sheet. Bake until tomatoes start to break down and caramelize, about 40 minutes.
Meanwhile, combine 1 Tbsp. olive oil, garlic, capers, lemon, parsley and red pepper in a bowl. When tomatoes finish roasting, add them (still warm) to the bowl. Stir to combine.
Increase oven temperature to 450 degrees. Toss ciabatta pieces in 1 Tbsp. olive oil and season with salt and pepper. Roast ciabatta in 9x13 inch baking dish until slightly golden, about 5 minutes. Remove ciabatta from oven and add tomato mixture to the baking dish, stirring to combine. Roast for another 10 minutes. Remove from oven and scatter salmon pieces over the top of the bread. Return baking dish to oven and continue roasting until salmon is cooked through, about 5 minutes. Serve immediately.