Preheat the oven to 425 degrees and line a roasting pan with foil. Mix the potatoes with olive oil and season with salt and pepper (I used roughly 1/2 tsp of both salt and pepper, but feel free to season to taste). Bake for 40-45 minutes (making sure to stir/flip the potatoes with a spatula once every 15 minutes), or until potatoes are golden brown and fork tender. Allow to cool, about 10 minutes.In a small bowl, mix together mayonnaise, sour cream, and cream cheese. Once smooth, add in celery seed, and stir. Set aside.In a large bowl, lightly mash half of the roasted potatoes with a fork or pastry cutter. Add in the rest of the potatoes, celery, bacon, and roasted red peppers (as well as any other add-ins you want). Add the dressing, and stir until the salad is evenly coated with dressing.Chill for at least 1 hour before serving.Enjoy!