Preheat oven to 350ºF, and line a baking sheet with parchment paper. In a medium bowl, combine the flour, oats, pecans, brown sugar, and cinnamon. Add the butter and stir until a moist crumb forms. Spread streusel evenly onto the lined baking sheet and bake in the oven for 8-10 minutes. Remove and allow to cool completely.

In a medium saucepan, heat the pears, water, and lemon juice over medium-high heat until they soften and become translucent, about 8-10 minutes. In a separate bowl, combine both sugars, cornstarch, and spices. Add mixture to the pears and continue cooking until it begins to thicken, about 2-3 minutes. Remove from heat and stir in the vanilla; set aside.

In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. In a separate bowl, lightly whisk the egg, then mix in the milk, yogurt/sour cream, and vanilla. Stir in the melted butter. Fold the wet mixture into the dry ingredients until just combined, avoiding over-mixing. Allow batter to sit for at least 5 minutes.

Heat a large nonstick skillet over medium heat with some vegetable oil. Once hot, pour 1/4 cup of batter onto the skillet. Cook pancake until little bubbles begin to form on the surface. Flip and cook the other side until golden brown, about 1-2 minutes. Repeat with the remaining batter.

Serve pancakes warm with pear topping and streusel. Add a scoop of ice cream, if desired.