How ... milk is there?
There's a lot of milk.
How ... flour is there?
There's a lot of flour.
How ... pancakes are there?
There are a lot of pancakes.
How ... biscuits are there?
There are a lot of biscuits.
How .... eggs are there?
There's an egg.
How ... tea is there?
There is some tea/There is a cup of tea.
How ... pizzas are there?
There are six pizzas.
How ... juice is there?
There's some juice/There's a glass of juice.
How ... bananas are there?
There are two bananas.