In a large mixer bowl, cream butter, margarine and sugars. Add egg, milk and vanilla and beat till light and fluffy. In medium bowl, stir together flour, baking powder, baking soda, salt and oats. Add to creamed mixture and mix till blended. Stir in chocolate chunks, pecans and coconut. Line Texas-shaped cookie pan with aluminum foil, spread cookie dough over whole pan, pressing to flatten. Bake in a 350-degree oven for 25 to 28 minutes. (The top of the cookie will still be slightly soft and moist, but will finish baking while still in the pan.) Allow to set in pan for 10-15 minutes. Remove from pan, lifting out with help of foil. Remove to wire rack to cool completely. Decorate as desired. Makes 1 Texas Cookie.