Sweet Potato Ricotta Cheesecake

Ingredients

• 1/4 cup pecans
• 1/4 cup minced crystallized ginger
• 1 cup all-natural gingersnap cookie crumbs (about 20 small cookies)
• 1 tablespoon canola oil
• 1 15-ounce container part-skim ricotta cheese
• 2 8-ounce packages nonfat cream cheese (at room temperature)
• 1 cup sweet potato purée or canned unsweetened pumpkin
• 1 cup date sugar
• 1/4 cup molasses
• 1 egg
• 1 teaspoon ground ginger
• 1/4 teaspoon ground nutmeg
• 1/8 teaspoon ground cloves
• 1 teaspoon ground cinnamon
• 3 egg whites (at room temperature)
• 1/4 teaspoon cream of tartar
• 1 tablespoon sugar
• Pinch of salt
• 2 cups nonfat plain yogurt
• 2 tablespoons sugar
• 1 teaspoon vanilla extract
• 16-20 pecan halves (for garnish)