Preheat the oven to 325 F. Line a 9 x 13 inch baking pan with parchment paper.
Make the shortbread. In a large bowl, combine the flour, graham cracker crumbs, brown sugar, and salt.
Add the cold cubed butter and cut it into the dry ingredients until the mixture looks like coarse sand with small pea sized bits of butter.
Add the honey and vanilla extract. Mix just until the dough comes together.
Press the dough evenly into the prepared pan. Dock lightly with a fork.
Bake for 25 to 30 minutes, until the top looks dry and the edges are golden brown. Cool completely in the pan.
Make the ganache. Place the chopped chocolate in a heatproof bowl.
Heat the heavy cream in a small saucepan over medium heat until steaming with small bubbles around the edges. Do not let it boil.
Pour the hot cream over the chocolate and let it sit for 1 to 2 minutes. Whisk from the center outward until smooth and glossy. Stir in the vanilla and salt.
Cover and chill the ganache in the refrigerator for 1 to 2 hours, until thickened to a scoopable texture.
Make the Italian meringue. Add the sugar and water to a small saucepan. Heat over medium heat until the sugar dissolves, then continue cooking until the syrup reaches 240 F. Do not stir once dissolved.
When the syrup reaches about 220 F, begin whipping the egg whites and cream of tartar in a stand mixer or with a hand mixer until soft peaks form.
When the syrup reaches 240 F, slowly stream it into the whipping egg whites, pouring along the side of the bowl and not directly onto the whisk.
Continue whipping on high speed until the bowl feels cool and the meringue is thick, glossy, and holds stiff peaks. Add the vanilla at the end and mix briefly to combine.
Whip the chilled ganache on medium speed until light, fluffy, and pipeable. Stop as soon as it holds soft peaks.
Assemble the bars. Cut the cooled shortbread into 18 bars. Spread or pipe the whipped ganache over the bars.
Top each bar with Italian meringue. Swirl decoratively with the back of a spoon or pipe it on for a cleaner look.
Torch the meringue until golden brown. Serve the same day for the best texture.