In a bowl, combine 1 1/2 cup flour, 1 1/2 cup old-fashioned oats, 1/2 tsp baking powder, 1/4 tsp cinnamon, a pinch of salt, and 1/2 tsp vanilla.
Add 3/4 cup cold cubed butter and 1/2 cup brown sugar and combine using a pastry cutter. Continue to cut through the dough until the butter is the size of peas.
Then mix in 3/4 cup chopped pecans. Then set it aside.
In a separate bowl, combine 9-10 sliced peaches, 1/3 cup brown sugar, 1 tbsp flour, 1/4 tsp cinnamon, 1 tsp vanilla, and 2 tbsp lemon juice.
In the bottom of a 9x13 inch baking dish spread 2 tbsp of cut butter. Then add the peach mixture on top.
Spread the crisp over the peaches and lightly compress it. Bake at 365 degrees Fahrenheit for 45 minutes. Serve warm with vanilla ice cream.