Combine granulated sugar, water, honey, and fresh lemon juice in a small saucepan over medium heat. Bring to a gentle boil, reduce the heat to medium-low, and simmer uncovered for 8 to 10 minutes until slightly thickened. Remove from heat, stir in the orange blossom water, and let cool completely to room temperature.

Pulse the shelled pistachios and ground cardamom in a food processor until finely minced with small textured pieces remaining. Preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius).

Unroll the phyllo pastry stack and trim the edges to fit the bottom of a 9x13 inch baking dish. Lay half of the dry phyllo sheets directly into the ungreased dish without buttering individual layers. Spread the minced pistachio mixture evenly across the entire surface, then cover with the remaining half of the dry phyllo sheets.

Using a very sharp chef knife, slice through all pastry layers to create diamond or square portions, cutting cleanly down to the bottom of the pan.

Slowly and evenly pour the warm melted butter over the entire surface of the sliced baklava, ensuring it runs into all cut lines and thoroughly permeates every layer.

Bake in the preheated oven for 45 to 50 minutes until the top is deeply golden brown, puffy, and visibly crisp across all seams.

Immediately remove the hot baklava from the oven and pour the cooled syrup evenly over the entire surface, paying special attention to the cut seams. Allow the baklava to rest uncovered at room temperature for at least 4 hours before serving.