Maple, Pear and Ricotta Parfaits

In a large nonreactive saucepan, combine the water, maple syrup and lemon juice. Add the pears and simmer over moderately low heat, turning occasionally, until tender, about 35 minutes. Remove from the heat and cool. Using a slotted spoon, transfer the poached pears to a work surface. Thinly slice the pears.

Bring the poaching liquid to a boil and stir in the sugar, butter and vanilla. Simmer over moderate heat until the liquid is reduced to 1/2 cup, 8 to 10 minutes.

In a bowl, whisk the ricotta until smooth and dollop a third of the cheese into 6 glasses. Top with half of the pears. Repeat with another dollop of ricotta and the remaining pears. Spoon the remaining ricotta on top and drizzle with the reduced poaching liquid. Sprinkle the pistachios on top and serve immediately.