The Earth's Crust.

                                                Model of the earth's crust: Pizza! 

                                                     

                                                    Pizza crust: Outer Core (molten). 

http://www.sodahead.com/living/which-type-of-pizza-crust-do-you-prefer/question-854075/?page=2&link=ibaf&q=&esrc=s

                                                             Sauce: Lower Mantle.

http://www.finecooking.com/recipes/no-cook-tomato-sauce-for-pizza.aspx

                                                           Cheese: shallow mantle.

http://fitness2at.com/2013/01/25/so-whats-the-plan/cheese-pizza/

                                                    Toppings: crust and lithosphere.

http://www.cs.umb.edu/~rkotla/