Heat oven to 250°F. Lightly spray an extra large rimmed sheet pan with cooking spray. Pour pecans halves into a large bowl. Set aside.
In a separate large bowl, add the egg whites and vanilla extract. Use an electric mixer to whip on medium-high speed until thickened and expanded around 2-3 minutes.
Pour the egg white mixture over pecans. Stir to fully coat the pecans.
To the pecans add the granulated sugar, brown sugar, cinnamon, salt, cloves (or allspice) and nutmeg. Stir until evenly coated. Pour the pecan mixture onto the pan.
Bake for 1 hour stopping to stir every 15 minutes.
Line a large baking sheet or clean, flat surface with parchment paper or wax paper.
Spread the pecans in a single layer and let stand to cool at room temperature. They should be dry to the touch before packaging for storage.
Notes
Sugar - You can use dark brown sugar in place of light brown sugar for a stronger molasses flavor. The results will be the same.
Heat - You could add chili powder or a pinch of cayenne pepper to the sugar mixture for extra heat.
Spices - You could adapt this recipe using pumpkin pie spice which includes ground cinnamon, ginger, nutmeg, cloves and allspice. When doing so, omit the spices called for in the recipe.
CandiedNuts - You can use this same technique for making candied almonds, hazelnuts, pistachios, cashews, peanuts or walnuts.
Bourbon Pecans - You can replace the vanilla with a tablespoon of bourbon.
Stir to Prevent Sticking - When stirring the pecans while they’re baking, be sure to push that spoon all the way to the bottom and rotate the pecans off the bottom of the pan so they'll roast evenly.