Preheat oven to 350°F (175°C). Prepare cookie sheets. Place porridge oats in a bowl, pour boiling water over. Stir; cover bowl with a large dinner plate; let stand 10 minutes. Let cool completely to room temperature. Combine butter and sugars, beat until light and fluffy. Beat in egg and vanilla. In a separate bowl, whisk together flour, baking powder, baking soda, salt and cinnamon. Gradually add flour mixture to butter mixture, beating until combined. Incorporate cooled porridge oats, carrots, raisins, and walnuts. Drop by tablespoonfuls onto cookie sheets. Bake 8-10 minutes, until centre of cookies are set.