Preheat oven to 375 degrees Fahrenheit and grease a 9x13" cake pan.

In the bowl of an electric mixer, cream together beaten eggs, sugar, melted butter, milk, and lemon juice.

Add flour, baking powder and salt and mix until incorporated. Pour in prepared pan.

Prepare topping by stirring together brown sugar, cinnamon, flour, melted butter, apples (spritz some juice from the lemons you already used over the diced apples) and nuts until combined. Sprinkle over cake batter and bake for approximately 25 minutes, or just until a toothpick inserted into the center comes out clean. Watch it closely so it doesn't overbake. Let cool slightly, then serve warm.