In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar until combined.
In a small bowl whisk together the 2 teaspoons heavy cream, egg yolk, and vanilla. Add this to the butter and sugar mixture and beat until incorporated. Scrape down the bowl and add the flour and salt until just combined. If you need more liquid, add a teaspoon more of heavy cream at a time until the dough comes together.
Turn out the mixture onto a lightly floured surface and form into an oblong disk. Wrap the disk tightly in plastic and refrigerate for 30 minutes.
Preheat the oven to 350°F (175°C). Butter the sides and bottom of a 9-by-13-inch glass or light-colored metal baking pan.
Lightly flour a work surface then roll out the dough into a large rectangle about the shape of the pan. Transfer the dough to the pan, and press into the bottom of the pan (do not press up the sides). If the dough cracks or splits, you can press it in pieces into the pan by hand.
Cover the dough with a sheet of parchment paper. Distribute the 1-⅓ cup of granulated sugar over the parchment paper-covered dough and bake for 11 minutes. Carefully remove the sugar and parchment paper, reserving the toasted sugar for the filling. Bake the uncovered tart base for another 5-7 minutes, until lightly golden. Transfer from the oven to a cooling rack. Keep the oven on while you make the filling.
Make the honeycomb bar filling
In a medium bowl, toss together the dried cherries, orange zest, cake flour, and salt. Set aside.
In a large saucepan over medium heat, stir together the sugar, heavy cream, maple syrup, and butter. Clip a candy thermometer to the side of the pan and bring the mixture to the soft ball stage, approximately 240°F (116°C) . Do not stir the mixture while it is coming to this stage.
Once the mixture reaches 240°F (116°C) , add the Cointreau and remove from the heat.
Fold the dry ingredients and the pistachios into the hot sugar mixture, then pour the mixture into the parbaked tart crust. Spread the filling evenly, and smooth the top.
Bake for about 15 minutes or until the bar is golden and bubbly. Remove from the oven and allow to cool completely before cutting.
Notes
Bars can be stored at room temperature, covered and sealed, for up to 4 days.