Make the pie crust through step 5 according to my directions and video tutorial in my pie crust recipe. Make pie dough in advance because it needs to chill in the refrigerator for at least 2 hours before rolling out (step 3). The recipe makes 2 crusts, and you only need 1 for this pie, so save the other for another pie.
Preheat oven to 375°F (190°C).
Remove 1 disc of pie dough from the refrigerator. On a lightly floured work surface, roll the dough out into a 12-inch circle. Make sure to turn the dough about a quarter turn after every few rolls. Carefully place the dough into a 9-inch pie dish. Tuck it in with your fingers, making sure it’s tightly pressed into the pie dish. Fold any dough overhang back into the dish to form a thick rim around the edges. Crimp the edges with a fork or flute the edges with your fingers. (Review how to crimp and flute pie crust if you need extra help with this step.) Line the pie crust with parchment paper. Crunching up the parchment paper is helpful so that you can easily shape it into the crust. Fill with pie weights or dried beans. (Note that you will need at least 2 standard sets of pie weights to fit.) Make sure the weights/beans are evenly distributed around the pie dish. Par-bake the crust for 10 minutes. Carefully remove the parchment paper/pie weights. Brush edges lightly with egg wash. Prick the bottom of the crust all over with a fork to create steam vents and return crust (without weights) to the oven for 7–8 more minutes or until the bottom is *just* starting to brown. (Review this how to par-bake pie crust page if you need extra help with this par-baking step.) Whisk the pumpkin, 2 eggs, and brown sugar together until combined. Add the cornstarch, salt, 2 and 1/2 teaspoons of the chai spice mix, heavy cream, and milk. Vigorously whisk until everything is combined. (You’ll have plenty of chai spice mix, so if you want to increase to 2 and 3/4 teaspoons, you can; the extra-deep flavor is delicious.)
Pour pumpkin pie filling into the warm crust. Bake the pie until the center is almost set, about 55–60 minutes. A small part of the center will be a bit wobbly—that’s OK. After 25 minutes of baking, be sure to cover the edges of the crust with aluminum foil or use a pie crust shield to prevent the edges from getting too brown. (See this post on the best tools for baking pies for how to make a pie crust shield out of foil.) Start checking for doneness at minute 50.
Once done, transfer the pie to a wire rack and allow to cool completely at room temperature for at least 3 hours before adding the meringue topping. Pie can be made through this step up to 1 day in advance; cover and keep at room temperature before adding the topping.
Place egg whites, sugar, and cream of tartar in a heatproof bowl. Set bowl over a saucepan filled with 2 inches of simmering water. Do not let it touch the water. (You can use a double boiler if you have one.) Whisk constantly until sugar is dissolved and mixture has thinned out, about 4 minutes. The mixture’s temperature taken with an instant read thermometer should be 160°F (71°C). If it’s not, keep cooking and whisking until thinned out and temperature is warm enough. Remove from heat. Add 1/2 teaspoon chai spice mix, and then, using a handheld or stand mixer fitted with a whisk attachment, beat on high speed for 5 minutes or until stiff glossy peaks form. Taste, and whip in a little more chai spice mix if you have any left/if desired. Spread meringue on top of cooled pie, or pipe with large star piping tip such as Wilton 1M. Serve immediately or store at room temperature or in the refrigerator, uncovered, for up to 8 hours before serving. If desired, toast the marshmallow topping with a kitchen torch just before serving. If you want to use the oven to toast instead, see detailed recipe Note.
Cover and store leftovers at room temperature for 1 day or in the refrigerator for up to 5 days.
