In medium nonstick skillet, melt 2 tsp (10 mL) of the butter over medium heat; cook leeks, 1 clove of the garlic, ¼ tsp (1 mL) each salt and pepper, stirring frequently, for about 6 minutes, until leeks are tender. Stir in thyme. Transfer to bowl and refrigerate to cool, about 15 minutes.
Meanwhile, in small saucepan, melt remaining butter and garlic over medium-low heat. Stir in vinegar and ¼ tsp (1 mL) of pepper. Set aside.
Unroll puff pastry. Place on parchment paper-lined baking sheet; using fork, poke entire surface. Brush mustard over pastry, leaving ½-inch (1 cm) border. Scatter leek mixture over pastry and arrange apple slices on top. Brush with butter mixture and scatter cheese over top. Bake in 400°F (200°C) oven for 15 to 20 minutes or until pastry is golden.
Drizzle: In small bowl, combine honey, thyme and mustard. Cut tart into pieces and drizzle with honey mixture.
