Bring everything to a boil over medium high heat. Reduce heat to medium low and cook until the blackberries have softened and the mixture has thickened, about 8 to 10 minutes. Remove from heat and allow to cool to room temperature.

Reserve 3 tablespoons of the liquid from the blackberry filling and set aside.

In the bowl of a stand mixer fitted with the whisk attachment, beat together the mascarpone, whipping cream, and vanilla at medium speed until thickened and able to hold a peak, about 1 to 2 minutes. Reduce the speed to low, add the sugar and honey and mix until incorporated (be careful NOT to overmix). Add the 3 tablespoons reserved blackberry filling and gently fold it into the mixture with a rubber spatula.

When making browned butter, it is best to use a stainless steel pan so that you can see the color of the butter change. Heat the butter in a large shallow frying pan over medium heat until melted. Swirl the pan around a bit every couple minutes to help it cook evenly. Over a period of several minutes, you’ll notice the foam at the top of the butter start to change from light yellow to a dark tan. Once it reaches the dark tan stage and the butter looks light brown and golden, smell it. It should smell nutty and similar to toffee. Remove from heat, stir in the honey, and set aside to cool to warm.

Meanwhile, in a food processor or blender, pulverize the graham crackers and pistachios until they form fine crumbs but NOT a paste. They should be dry and crumbly. Combine the brown butter mixture and the graham cracker mixture together in bowl with the sugar and the salt and stir until mixed. Then press into a 10-inch pie dish to form the crust.

Empty the blackberry filling into the crust and spread to even it out. Then add the blackberry whipped cream mixture on top of the blackberry filling and spread it out with a rubber spatula to cover the filling (you can use the back of a spoon to make some fun swirls on top, if you want.) Garnish with the chopped pistachios, honey, and blackberries and place it in the refrigerator for at least 3 hours before slicing and serving. Will keep up to 1 week in the refrigerator in an airtight container, but be aware that the crust will soften the longer it sits.