1. Grate the cheeses at home - store-bought shredded/grated cheeses (especially parmesan cheese) don't melt as well due to the anti-caking agent used. Block cheeses are more economical anyway! It's a win-win.
2. Use fan-forced function to bake eggplants - I find fan-forced works better when baking 3 trays of eggplants as the distribution of heat is more even. However, all ovens are different so it might work differently to you.