Preheat oven to 350°F (175°C). Lightly grease a 9-inch pie pan with cooking spray. Melt the butter in a microwave-safe bowl. Once melted, set it aside to cool for 5 minutes to prevent a greasy crust.: As the oven warms and the air takes on that dry, warm scent, you can feel the kitchen gearing up. The melted butter should be warm not hot, so when you mix it into the crumbs it moistens evenly without separating, and you will notice the crumbs darken slightly and glisten. Cooling the butter prevents it from making the crust oily, which would ruin the texture. If you skip the cooling step you risk a greasy, loose crust, so be patient. Listen for the quiet hum of the oven as it settles into temperature while you prep the crumbs.
In a blender or food processor, process graham crackers into fine crumbs, reblending any large chunks. Measure the crumbs and transfer to a large bowl. Add the sugar and salt. Pour in the melted butter and mix until well combined.: The motor whirs and a warm sweet aroma of crushed graham crackers fills the air, signaling progress. Aim for uniformly fine crumbs so the crust binds and bakes evenly; any coarse pieces will create weak spots. Mixing in the granulated sugar and salt ensures every bite is balanced, and the melted butter should coat the crumbs until they clump slightly when pressed. A common mistake is under processing, leaving large flakes that prevent proper compression, so reprocess any stubborn chunks until smooth.
Pour crumb mixture into prepared pan. Press crumbs firmly along the sides and bottom of the pan using your fingers. To create a solid crust, use the bottom of a flat 1-cup measuring cup to thoroughly compress the crumbs. Bake for 10 minutes, then remove from oven and allow to cool completely. You can prepare and bake the crust up to 24 hours in advance. Cover with plastic wrap and store at room temperature.: When you press the crumbs they should feel compact and hold their shape; the surface will look slightly darker and sheen faintly from the butter. Baking produces a toasty, slightly nutty aroma and the crust firms to a light crunch. Use steady pressure with the measuring cup to avoid cracked edges, and once baked allow it to cool fully so the hot warmth does not destabilize the custard later. If you skip the cooling you may end up with a soggy interface between crust and filling.
In a medium pot, off heat, combine the sugar, salt, and cornstarch. Whisk together until well mixed. Add egg yolks and whisk until combined. While whisking constantly, pour in coconut milk followed by heavy cream. Continue whisking until all ingredients are fully integrated. Place pot on stove over just below medium heat. Whisk occasionally as the mixture heats up, alternating between whisking and using a rubber spatula to scrape the sides and bottom of the pot to prevent cornstarch from sticking.: Off heat mixing prevents the yolks from scrambling, and you will see the dry ingredients soften into a pale paste before the liquids are added. As the pot warms you can smell the sweet coconut beginning to open up, and the mixture will gradually lose shine and thicken. Scraping the sides keeps the cornstarch from clustering and avoids burnt pockets on the bottom. A common error is heating too quickly which creates lumps, so keep the heat gentle and be attentive to the gradual change in texture.
As soon as the mixture begins to thicken, start whisking constantly. When you see large bubbles forming in the center, set a timer for 1 minute and continue whisking constantly. If bubbling becomes too intense, reduce heat slightly. The mixture should thicken significantly, reaching a pudding-like consistency. After 1 minute, remove pot from heat.: This is the sensory moment you will remember, when the custard moves from thin to viscous and those large central bubbles signal full gelatinization. The sound changes to a soft rolling simmer and the aroma deepens into a warm, concentrated coconut scent. Whisking continuously during this phase prevents scorching and ensures a smooth body. If you stop whisking you may get a grainy texture or scorched bits, so keep stirring and adjust the flame if it roars too vigorously.
Whisk off the heat for another full minute. Add the butter and whisk until fully melted. Then, add vanilla and coconut extract to taste. Whisk until the mixture is completely smooth.: Off the heat the custard calms and becomes glossy as the butter is whisked in, lending silk and shine. Adding the extracts now preserves their fresh aromatic qualities, and a quick whisk distributes them evenly so there are no pockets of concentrated flavor. You will sense a thicker, almost velvet texture. A typical mistake here is adding extracts too early to boiling liquid which can dissipate their nuance, so hold them back until the pot is off the heat.
Use a spatula to transfer mixture from the pot into the cooled crust, smoothing the top with the spatula. Gently place a piece of plastic wrap directly on the surface of the filling, pressing lightly to create a seal. This will prevent a skin from forming on the pudding. Refrigerate for at least 8 hours or until the filling is fully set.: As you spread the warm custard it will settle into the crust with a glossy surface, and the kitchen will smell richly of toasted coconut and vanilla . Pressing plastic wrap directly on the custard stops a membrane from forming and keeps the top perfectly smooth when chilled. Refrigeration firms the filling and deepens the flavors; slicing too early will result in a loose filling that oozes rather than slices cleanly. Patience here yields beautiful presentation.
Pour the heavy cream, powdered sugar and vanilla into a bowl attached to a stand mixer. Whisk on low speed to combine the ingredients, then gradually increase to high speed. Whisk until medium-to-stiff peaks form, about 2–4 minutes. Be careful not to overbeat. Smooth the whipped cream over the pie.: As you whip the cold heavy cream the texture will change from liquid to billowy peaks, and the sweet aroma of powdered sugar will be faintly present. Watch closely because the transition from soft to stiff peaks happens fast; when the whisk lifts the cream should hold shape without collapsing. Overbeating yields a grainy look and a broken texture, so stop as soon as the peaks are stable yet still glossy. Spreading the whipped topping creates a cloudlike contrast to the dense custard below.
Toast the unsweetened coconut in a large skillet over low-to-medium heat, stirring frequently, until mostly golden brown, about 3–6 minutes. Remove from heat and transfer to a plate to cool completely. Once cooled, sprinkle evenly over the pie.: Toasting the shredded coconut releases nutty aromas and a warm golden color that adds crunch and visual contrast. Keep stirring so it browns evenly and remove it quickly as residual heat continues to cook it on the pan. Once cooled, the toasted flakes remain crisp on top of the creamy pie. A common mistake is leaving it on the heat unattended, which can turn it from golden to bitter in seconds.