Preheat your oven to 350ºF and line the bottom of a 9-inch round cake pan with parchment paper.
For the cake: Mix all the dry ingredients in a bowl and set aside.
In another bowl, beat coconut oil, sugar, and vanilla extract until light and fluffy.
Add eggs one at a time, mixing well after each addition. Slowly pour in almond milk.
Gently fold in the dry ingredients until just combined. Don't overmix!
Transfer batter to the prepared pan and bake for 45 minutes or until done.
For the candied lemons: Simmer lemon slices in water, lemon juice, and sugar until soft and translucent. Sprinkle with turbinado sugar.
Let the cake cool for 10 minutes before removing from the pan and cooling completely.
Meanwhile, prepare the whipped cream frosting by whipping cream, powdered sugar, lemon juice, and vanilla extract until stiff peaks form.
Once the cake is cool, frost it generously with the whipped cream frosting.
Decorate with candied lemon slices, lemon zest, and poppy seeds.