Prehaet 350º. Grease sides and bottom of a 8x11” baking dish.
In a large bowl, combine oats, flour, brown sugar, 1 teaspoon cinnamon, and bakng soda. Stir in melted butter until well blended. Reserving 1 cup oat mixture, press remaining oat mixture into prepared pan. Ina medium bowl. Combine reserved oat mixture, raisins, walnuts, and marmalade. Spread raisin mixture evenly over the oat mixture in pan. Bake 25-30 min or until lightly browned. While still warm, cut into 1” squares.
In a small bowl, combine confectioners sugar, ¼ tsp cinnamon, and milk, stir until smooth. Drizzle over warm squares. Cool completely in pan, Store in an airtight container.