With 9 cups of milk, \(\frac{\mathrm{9} }{\mathrm{2}}\) = \(4\frac{\mathrm{1} }{\mathrm{2}}\) or four full batches can be made.
However, with nine eggs, only \(\frac{\mathrm{9} }{\mathrm{4}}\) = \(2\frac{\mathrm{1} }{\mathrm{4}}\) or two full batches can be made.
At most, only two batches can be made with the given ingredients.