Rosemary Whipped Cream

Combine the heavy cream and rosemary in a small saucepan. Cover and heat over medium until small bubbles begin to form on the surface and steam forms. Let steam for one minute and then remove from heat and refrigerate until cold, letting rosemary steep.

Just before serving pie, remove rosemary sprigs and transfer cream to the bowl of a stand mixer fitted with the whip attachment (or use a large bowl and handheld electric mixer). Beat on medium-high speed until thickened. Add sugar and vanilla extract and continue to beat just until cream holds its shape, being careful not to overbeat.

Pie Crust

In a large bowl, whisk together the flour, coconut sugar, salt, xantham gum (if using), baking powder, and rosemary. Toss in the butter to coat, and then flatten each chunk between your fingers. Add the sour cream and fold in just enough to moisten the dry ingredients; the dough should still be somewhat shaggy. Finish kneading the dough together by hand just until cohesive, adding ice water a teaspoon at a time if needed.

Divide dough in half. Turn each half out onto a piece of plastic wrap, press into a disc, and wrap. Refrigerate for 30 minutes.

Remove one portion of dough from the refrigerator and place on a large, floured sheet of parchment. Dust surface of dough with flour and roll out into a rectangle about 1" thick, adding extra flour if it begins to stick. Fold the dough onto itself like you would a letter. Dust again with flour and repeat the rolling and folding process twice more. Finally, roll the dough out into a 12-inch round and carefully transfer to pie plate. Refrigerate while prepping remaining dough and filling, at least 30 minutes.

Repeat the same rolling and folding process with the second portion of dough, and then roll into a 12-inch circle and cut into even strips (I did six strips, 2" wide). Use parchment to transfer to a baking sheet and refrigerate while prepping filling and egg wash.

Rhubarb-Peach Filling

In a large bowl, toss together the peaches, rhubarb, sugar, arrowroot starch, vanilla extract and sea salt until thoroughly combined. Set aside.

Egg Wash

In a small bowl, whisk together the egg white and water.

Assembly and Baking

Preheat oven to 425ºF.

Remove pie crust from refrigerator and pour filling into crust. Carefully arrange strips of dough accross the top in a lattice design. Trim the strips to the edge of the pie plate, and then fold the bottom crust overhang over the top of the lattice, press lightly to seal, and crimp edges. Brush dough with egg wash and sprinkle with demerara sugar.

Bake pie in preheated oven for 15 minutes, and then reduce heat to 350ºF and bake another 50-60 minutes, until top is golden-brown and filling is bubbling. Tent with foil if crust begins to brown too quickly.

Remove from oven and allow to cool for at least a few hours before serving. Serve with rosemary whipped cream. Cover any leftovers with plastic wrap or aluminum foil and store in the refrigerator.