To find out how much flour is used in the body of the dessert, subtract the amount of flour needed for the crumble from the total amount of flour required.
Total flour required: \( \frac{3}{4} \) cups
Flour for crumble: \( \frac{1}{4} \) cup
Now, perform the subtraction:
\[ \text{Flour for the body} = \frac{3}{4} - \frac{1}{4} = \frac{2}{4} = \frac{1}{2} \]
So, the amount of flour used in the body of the dessert is \( \frac{1}{2} \) cup.
Therefore, the answer is \( \frac{1}{2} \) cup.