A grammar summary of all the basic exclamation constructions.

Notice that when we use a noun, we may need the article (a/an) or not. That depends on the noun. Countable singular nouns use article, plural and uncountable nouns don't.

- What (a/an) + noun
    What a day!
    What flowers!
    What performance!
- What What (a/an) + adjective + noun
    What a delicious pizza!
    What pretty girls!
    What excellent wine!
- What What (a/an) + (adjective) + noun + V
    What a (boring) book to read!
- What What (a/an) + (adjective) + noun + other sentence elements
    What interesting stories your grandfather tells!
- How + adjective
    How exciting!
- How + adjective + a/an + noun*
    How delicious a pizza!
    How boring a book!
- How + adverb of manner + subject + verb
    How quickly time passes!
- How + adjective + (a/an) noun + other sentence elements
    How nice a balcony you have in your house

*we only use this construction with singular countable nouns because we need to use the article (a/an). But the other construction (what a/an/x adjective + noun) is more normal for this, so you can forget about this construction.