For the cake and peaches: Heat a grill to medium-high heat and oil the grates with vegetable oil.
Grill the cakes until dark grill marks appear, 4 to 5 minutes per side. Grill the flesh side of the peaches until dark grill marks appear, about 5 minutes. Set aside.
In a cold stand mixer bowl using a whisk attachment, combine the whipping cream, mascarpone, honey and vanilla. Whip to medium-stiff peaks. Set aside.
For the cherry coulis: In a blender, blend the cherries, champagne vinegar, dark brown sugar and 2 tablespoons water until the mixture is smooth. Transfer to a small saucepot and heat until the sugar dissolves. Strain out any solids if necessary and set aside to cool.
In each of 4 shallow bowls, put a small puddle of coulis. Add a cake on top of that, followed by the grilled peaches and a nice dollop of the mascarpone cream. Garnish with a happy helping of crushed pistachios.