The interiors of Earth and other planets were “cooked” by processes of accretion and differentiation and can be “tasted” by geochemical sampling at the surface and remote geophysical observations of physical properties at depth. Mineral physics experiments and simulations seek to reverse-engineer the recipes that generate the features we detect in the deep Earth today. Because Earth and other planets are almost entirely composed of materials at high pressures and temperatures, the key to translating geophysical observations to structure and composition is the dependence of mineral stability and physical properties such as density, elasticity, and transport properties on composition and thermodynamic conditions. I will discuss recent observations of chemical reactions and properties of minerals relevant to Earth’s mantle, and implications of these experiments for the compositions of layers and regions in the deep Earth.