Preparation Preheat oven to 375 degrees. In a bowl combine crab meat, pepper, chives, egg, mustard, mayo, old bay (I use a good deal of old bay). Stir to mix and add panko, do not add too much you just want enough for the mixture to bind together. remove stems from the mushrooms, using a spoon hollow out the centers and then toss mushrooms with salt, pepper, and olive oil. Using about 1-2 tablespoons of filling stuff crab filling into the mushrooms. Place on a sheet pan lined with aluminum foil and bake for 20-25 minutes or until the filling is golden. You don't want to over cook the mushrooms or they will be too moist and the filling will become soggy. For the Horseradish Dipping Sauce: Stir to combine. For a fuller fat version you can use more mayo or substitute the mayo in this recipe for horseradish cream.