Lemon Oat Bars

For the crumble

• 160 g plain flour
• 100 g porridge oats
• 110

Make the crumble by mixing the flour, oats, butter, sugar, bicarbonate of soda and salt in a food processor until just combined, or rub in by hand.

Tip half of the crumble into the baking tin (a square deep baking tin 20cm square, lined so it comes up two sides for easy removal of the bake once cooked) then press down firmly and bake at