This showstopper is a favorite of ours, filled with morels, asparagus, ramps, spring onions, and Fontina Val d'Aosta.  

Suggestion: One option is to bring the quiche to room temperature and serve.

But it is arguably better if you cut and reheat the Quiche in a pre-heated hot, 450F oven. Slice while cold, then place only the slices you are presently serving on a sheet pan. Bake on the upper shelf of your oven for 3-4 minutes. The exposed filling should sizzle and brown slightly, while the re-warmed custard will become incredibly fragrant and silken, without actually melting.  Be careful not to burn the crust - use a timer!