Preheat oven to 350°. Prepare 9in pie plate by spraying with non-stick spray or greasing.
Make crust by mixing almond flour with melted butter, salt and rosemary. Press firmly into bottom of pie plate and upsides. Bake for 15 minutes until slightly golden brown. Let cool.
While pie crust is baking, begin making the filling. In a medium sized pot, bring cranberries, sugar, orange peels and salt to a gentle boil. Reduce to a simmer and stir frequently to prevent burning.
After a few minutes, gently press the cranberries against the side of the pot with a rubber spatula to release their juices. Do this carefully so you don't get burned. If cranberries resist bursting with gentle pressure, simply cook another minute until they are softer.
Remove orange peel and transfer cranberry mixture to a high powered blender. Blend for about 1 minute on high until smooth. Alternatively, you can blend in the pot with an immersion blender.
Strain cranberry mixture through a fine mesh sieve to remove pulp. In a bowl, combine cranberry mixture with butter until melted.
Whisk eggs into warm cranberry mixture one at a time. If the mixture is too hot to touch, then it is too warm and will scramble the eggs. Wait until the mixture is warm but not hot to the touch to mix.
Pour mixture into pie crust and bake for 20-25 minutes. When it's done it will look slightly fluffy all over. If the filling is still liquid looking then bake for another 3-4 minutes until set. Let cool completely before serving. Pie can be kept at room temperature for up to two days.