Preheat the oven to 175 degrees. In a large skillet, heat 3 tbsp. EVOO, three turns of the pan, over medium-high. Season the veal with salt and pepper and dust with flour. When the oil ripples, add half the veal to the skillet and cook until browned, about 2 minutes per side. Transfer to a rimmed baking sheet and place in the oven. Repeat with the remaining veal scallops.
Add the butter to the skillet; when it foams, add the mushrooms and cook, stirring, until browned, 5 minutes. Add the shallots, thyme and garlic; season and cook, stirring, until soft, 2 to 3 minutes. Add the marsala and deglaze, swirling the skillet. Add the cream, reduce the heat to low, and simmer until the sauce thickens, about 2 minutes.
Arrange 2 slightly overlapping toast points on each plate and top with the veal scallops. Spoon the mushroom sauce over the top and garnish with chives.