Remove the thawed phyllo from the fridge 1 hour before using. When working with the phyllo dough, only remove the sheets you immediately need, keeping the other sheets covered in plastic wrap, then a damp cloth.
Preheat the oven to 350 degrees F. Melt 1/2 stick (4 tablespoons) of the butter in a small saucepan.
Toss together the chopped pecans and cinnamon in a bowl. Set aside.
Thoroughly butter a rectangular baking pan with the melted butter. Make sure the sheets of phyllo will generally fit in the pan. (If they're a little bigger, that's okay; if they're much bigger, just trim them with a sharp knife.)
Butter the top sheet of phyllo with melted butter, then grab it and the unbuttered sheet below it. Flip the sheets over and set them in the pan buttered-side down. Press them lightly into the pan. Repeat this twice more, so that you have 6 sheets of phyllo in the pan, 3 of the sheets buttered.
Sprinkle on enough pecans to make a single layer. Butter 2 sheets of phyllo and place them on top of the pecans buttered-sides down. Add more pecans, then 2 more buttered phyllo sheets. Repeat this a couple more times, or until you're out of pecans. Top with 4 more buttered phyllo sheets, buttered-sides down. Butter the top of the final sheet.
Cut a diagonal diamond pattern in the baklava using a very sharp knife. Bake until very golden brown, about 45 minutes.
While the baklava is baking, combine the honey, sugar, vanilla, 1/2 cup water and the remaining 1 stick butter in a saucepan. Bring the mixture to a boil, then reduce the heat to low.
When you remove the baklava from the oven, drizzle half of the honey mixture evenly all over the top. Allow it to sit and absorb for a minute, then drizzle on a little more until you think it's thoroughly moistened. You'll likely have some of the honey mixture leftover, which you can drink with a straw. Just kidding.
Allow the baklava to cool, uncovered, for several hours. Once cool and sticky and divine, carefully remove from the pan and serve with coffee (or give as gifts!).
To thaw the phyllo dough, remove the package from the freezer and place it in the fridge for 24 hours to thaw.