Preheat oven to 350°.
Melt 1 tablespoon butter in a small skillet over medium heat; add pecans. Cook 3 minutes or until toasted, stirring often. Set aside, and let cool.
Combine 3/4 cup brown sugar and 2 tablespoons butter in a bowl; beat at medium speed of a mixer 3 minutes. Add milk and 1 tablespoon bourbon; beat well. Combine 1 1/4 cups flour, baking powder, cinnamon, and salt; gradually add to sugar mixture, beating well. Spoon batter into an 8-inch square baking pan coated with cooking spray.
Combine remaining 1/4 cup flour, remaining 2 tablespoons bourbon, and 2/3 cup brown sugar in a small bowl; sprinkle over batter. Top with reserved toasted pecans. Pour boiling water over batter (do not stir). Bake at 350° for 35 to 40 minutes or until cake springs back when touched lightly in center. Let stand 10 minutes. Serve warm with ice cream.