Preheat oven to 160C (320F).
Grease and line with baking paper a 23cm square baking pan.
Place flour, rice, sugar,fennel seeds and orange zest in a food processor and pulse 2-3 times to combine well.
Add butter and process until dough just comes together.
Press into prepared pan, score into squares, pierce each square with a fork, and place in refrigerator for 10 minutes.
Bake for 20-30 minutes, until very lightly golden, but not browned. Cut into squares along the score lines while still hot.
Cool in pan.