Make the cake.  Preheat oven to 350 degrees F, 325 degrees F convection.  Oil a 9 by 13 inch baking pan.

In a large bowl, whisk together oil, sugar, vanilla, lemon zest, and eggs until well combined.  Whisk in the flour and almond milk alternately, beginning and ending with the flour.  Stir in the poppy seeds and blueberries, and pour into the prepared pan.

Bake about 30 minutes, until golden brown, and a toothpick inserted in the center comes out clean or with a few moist crumbs.  Cool completely in pan.

Once cool, make the icing.  In a medium, microwave safe bowl, place coconut butter, milk, vanilla, lemon juice, and honey or syrup.  Microwave on high in 30 second increments, stirring in between, until fully melted.  Stir in the lemon zest.  If the icing is too thin, stir in a tiny bit more coconut butter.  If it is too thick, stir in more milk, a little at a time.  Pour icing over cake, spread into an even layer, and sprinkle with poppy seeds.  Allow icing to set for about an hour before slicing and serving.

Cake may be stored in an airtight container at room temperature for up to 3 days, or frozen, wrapped in parchment and foil and placed in a zipper bag for up to 3 months.  Thaw in the microwave about 1 minute.