Sophie's Scroggin Lunch Biscuits

(from a book called School Lunches and after school snacks - these are the much maligned home made biscuits!)

Makes a huge quantity.

200g butter
1/4 cup peanut butter
1/2 cup sugar
1 cup packed brown sugar
2 large eggs
1 tsp vanilla or almond essence
1 1/2 cups plain flour (if using instant oats use 1/4 cup less flour)
1 tsp baking soda
2 cups rolled oats
1 cup chocolate chips
1 cup sultanas
1/2 cup chopped walnuts - I leave these out

Heat oven to 180ºC. Mix the softened butter and the next five ingredients together in a large bowl, then stir in the flour and baking soda. Add everything else and mix, using a wooden spoon or your hand. Shape with two spoons or put flattened rounds of mixture on baking paper-lined trays, leaving space for spreading. Bake in batches for about 12 minutes or until lightly browned, then cool on a rack.