Make the Homemade Pie Crust recipe, which yields two single pie doughs. Divide in half, making two discs, wrap in plastic wrap and refrigerate for 45 min-hr.
Remove one disc from the fridge to make the decorative pie leaves. Sprinkle working surface lightly with flour and rolling out to ¼-1/8 inch thickness. Use a real fall leaf from outside or a stencil to trace and cut out leaf designs. Take a sharp knife and gently scratch designs into the leaves. Place leaves on a parchment paper lined tray and set in the fridge to chill until ready to decorate pie.
Roll out the second half of the pie dough and gently lower into your pie pan. Don't trim any of the of overhanging dough. Instead carefully fold it back under itself to create a thicker layer along the edge or lip of the pan. Place the pan into the fridge to chill for 20 minutes.
Peel two medium sweet potatoes and chop into cubes. Place into a large sauce pan or small pot, add enough water to submerge the pieces. Boil on medium high for about 30-35 minutes until super soft. Remove from heat and stir in brown sugar and melted butter. Use an immersion blender or stand blender to puree until smooth. Set aside to cool.
Make filling by whisking heavy cream, coconut milk, beaten eggs, rum, spices, and flour in a medium bowl. Pour cream mixture into the mashed sweet potatoes. Transfer to a large blender and mix until smooth.
Remove pie pan from fridge and pour in the filling. Level with an offset spatula.
Remove decorative pie dough leaves from the fridge. Arrange them onto the edge of the pie crust by brushing the bottoms lightly with cold water and softly pressing them onto the bottom layer of dough.
Brush the leaves with egg wash and then sprinkle with sparkling or coarse sugar,
Place the filled pie into the fridge to chill for an hour. This extra chilling step helps the crust maintain its shape during baking.
Preheat oven to 375 F (190 C). Remove pie form the fridge and place pan onto a cookie sheet. Transfer to the middle rack of the oven and bake for 15 minutes.
Reduce heat to 350 F (180 C) and bake for an additional 30-35 minutes. The pie is baked with the outer edges of the pumpkin pie are set and the very center is still slightly jiggly. If there is a wave or big ripple when you nudge the pan, bake the pie for an additional 8-10 minutes.
Remove pie pan from the oven and set directly into wire cooling rack. Allow pie to cool completely before serving 2-3 hrs. Cover with foil and refrigerate.