Rinse tangerines well and place them whole in a large pot.
Cover with water and simmer gently until the fruit is very soft, about 20–25 minutes.
Remove from the pot and allow the tangerines to cool.
Peel the fruit, discard seeds, and transfer the softened pulp, juices and rinds to a blender.
Blend until smooth, adjusting texture as desired.
Use immediately or portion into containers or freezer bags for storage.
Preheat oven to 350°F and prepare a 9-inch cake pan with parchment or light greasing.
In a large bowl, whisk together tangerine puree, eggs, sugar, honey, olive oil, and amaretto until smooth.
Stir in citrus zest.
In another bowl, combine almond flour, baking powder, and salt.
Add dry ingredients to wet mixture and stir just until combined.
Pour batter into prepared pan and smooth the surface.
Bake 35–40 minutes, until the cake is lightly golden and set in the center.
Cool completely before dusting with powdered sugar or drizzling with citrus glaze.