Preheat the oven to 350 degrees F (175 degrees C).

Combine brown sugar, white sugar, margarine, and oil in a large bowl; beat with an electric mixer until creamy. Add egg, salt, baking soda, cream of tartar, vanilla extract, and butter flavor; mix well. Add flour and mix well. Stir in oats, chocolate chips, butterscotch chips, rice cereal, candied fruit, and coconut; cookie dough will be difficult to stir.

Drop cookie dough onto baking sheets using spoons or a small ice cream scoop.

Bake in the preheated oven until edges are set and lightly golden, 8 to 12 minutes. Transfer to wire racks to cool.