• Preheat the oven to 350 degrees and line 9" x 9" pan with parchment paper.    (Hint:  to make parchment paper fit more easily wad it up and wet it.  Wring out excess water and fit it into the pan.)
• Cream butter and sugar together in a large mixing bowl with an electric mixer.
• Add egg and vanilla extract and beat mixture well.
• With a spatula, fold the chopped apples into the creamed mixture. (Don't use mixer after the first two steps).
• In a medium size bowl whisk the dry ingredients together.
• Alternate adding 2 tbsp milk and 1/2 of the dry ingredients, stir in and repeat with other 2 tbsp milk and the rest of the dry ingredients.  Stir just until combined with a mixing spoon or spatula only.
• Place cake batter into prepared pan. Top with crumble topping below.

Crumble Topping:

• In a medium size bowl combine the brown sugar, flour, ground cinnamon and chopped nuts.
• Melt butter and add to the dry topping ingredients.  You can melt butter in a microwave safe dish, covered,  for about 20 seconds on high.
• Stir all ingredients together and crumble evenly over the cake batter.  Mixture should be fairly chunky.  Bake for 30 minutes or until toothpick comes out clean with a few crumbs in center of cake.
• Let cake cool until it is just warm before serving.
• Serve as is or add a little whipped cream or a scoop of vanilla ice cream.
• Store covered at room temperature up to 3 days.  May refrigerate any leftovers for 7 days. Cake freezes well for up to 3 months.