Learn French: Ce que la nuit est splendide !

In English, we put the adjective right after "How" ("How splendid the night is!"). But in French exclamations with ce que, que, or comme, you keep the normal sentence order (Subject + Verb + Adjective) and just put the exclamative word at the front. So it translates literally to "How much the night is splendid!"

Could I use que or comme instead of ce que in this sentence?

Yes, absolutely! You could say Que la nuit est splendide ! or Comme la nuit est splendide ! They all mean exactly the same thing. Ce que is just a bit more informal and highly common in everyday spoken French, while que can sound slightly more literary.

I usually translate ce que as "what". Why does it mean "how" here?

When placed at the very beginning of an exclamation, ce que stops acting as a relative pronoun ("what" or "that which") and instead becomes an adverb of intensity. In these exclamatory sentences, it translates to "how" or "how much" to emphasize the adjective splendide.

Since la nuit is feminine, shouldn't splendide have a feminine ending?

It does! However, splendide is an adjective that already ends in an "e" in its base masculine form. Because of this, it doesn't take an extra "e" in the feminine form, so the spelling stays exactly the same.