Combine 1/3 cup brown sugar, pecans, cinnamon and nutmeg in a small bowl; set aside.
Gradually add 1 1/2 cups sugar, beating 5 to 7 minutes. Add eggs, one at a time, beating just until yellow dissapears.
Combine flour, baking powder, baking soda and salt in another bowl. Add sour cream and flour mixture alternately to butter mixture, beginning and ending with flour mixture; beat at low speed after each addition just until mixture is blended. Stir in one teaspoon vanilla.
Spoon half of batter into a greased and floured 12-cup Bundt pan. Arrange apple slices over batter, then spoon half of brown sugar mixture over apples; gently press into batter. Top with remaining batter, then sprinkle with remaining brown sugar mixture.
Bake at 350° for one hour or until a toothpick inserted in center comes out clean. Cool in pan on wire rack.
Heat 2 tablespoons butter in a small saucepan over medium heat until butter starts to brown. Remove from heat and stir in remaining 1/2 cup brown sugar, milk and one teaspoon vanilla. Stir until smooth; drizzle glaze evenly over cake.