Preheat oven to 350 F. Spray at 9-inch pie plate with cooking spray. Combine flour and salt, set aside. Melt chocolate in a double boiler over hot water; remove from heat. Mix in butter and sugar. Add egg and vanilla to chocolate mixture in pan; mix until smooth. Stir flour mixture into chocolate mixture. Spread butter in prepared pie plate. Bake until set, about 15 minutes. For topping, mix nuts, peanut butter chips, marshmallows and coconut. Sprinkle over brownie layer. Bake for 10 minutes or until pizza pulls away from sides of pan. Cool before cutting.