Low FODMAP Lemon Crumb Cake - FODMAP Everyday

Ingredients

• 1 1/3 cups (194 g) low FODMAP gluten-free all-purpose flour, (such as Bob’s Red Mill 1 to 1 Baking Flour)
• ½ cup (99 g) sugar
• 1 tablespoon lemon zest, (made with a rasp-style zester)
• Pinch salt
• ½ cup (1 stick; 113 g) cold unsalted butter, (cut into pieces)
• 1 ½ cups (218 g) low FODMAP gluten-free all-purpose flour, (such as Bob’s Red Mill 1 to 1 Baking Flour)
• ½ teaspoon baking soda
• ¼ teaspoon salt
• ½ cup (1 stick; 113 g) unsalted butter, (at room temperature, cut into pieces)
• 1 cup (198 g) plus 2 tablespoons sugar, (divided)
• 1 ½ tablespoons lemon zest, (made with a rasp-style zester)
• 1 teaspoon vanilla extract
• 3 large eggs, (separated)
• ½ cup (128 g) thick lactose-free plain yogurt, (such as Siggi’s)
• ¾ cup (180 ml) Low FODMAP Lemon Curd
• Confectioners’ sugar; optional