Preheat the oven to 350 degrees F. Line an 8-inch square baking pan with parchment paper.

In a mixing bowl, whisk together the eggs, melted coconut oil, pure maple syrup, and lemon juice until well-combined.

Add the almond flour, baking soda, and sea salt and stir well until a thick dough forms. 

Stir in the chopped apple until well-incorporated.

In a separate bowl, stir together all of the ingredients for the streusel topping. It will be fairly dry and crumbly - this is normal.

Transfer half of the coffee cake mixture to the lined baking sheet and smooth it into an even layer. Follow this up by sprinkling half of the streusel mixture over the cake batter evenly. Repeat for the remaining cake batter and streusel mixture (it’s normal for the cake batter to be thick and sticky, so do your best to smooth the layers with a rubber spatula, but it doesn’t need to be perfect!).

Cover the coffee cake with foil and bake for 30 minutes. The foil will protect the topping from burning. Remove the coffee cake from the oven and discard the foil. Place the coffee cake back in the oven and continue baking without the foil for another 15 to 20 minutes, or until the cake has set up and is golden-brown around the edges.

Allow the coffee cake to cool for at least 15 minutes before slicing and serving.