Preheat oven to 350℉ (180℃)
Peel and grate an apple. Place in a bowl with the raisins and vanilla extract. Toss until combined. Set aside for later.
1 ½ Cups Raisins, 1 large Apple (Granny Smith, Honeycrisp, etc...), 1 teaspoon Pure Vanilla Extract
In a separate bowl, whisk together flour, cinnamon, baking soda, salt, brown sugar and granulated sugar.
1 Cup Gluten-Free Flour, ½ Cup Granulated Sugar, ½ Cup Light Brown Sugar, ½ teaspoon Baking Soda, ½ teaspoon Ground Cinnamon, ½ teaspoon Salt
Add egg and melted butter to the bowl with the flour mixture. Stir until combined.
½ Cup Unsalted Butter, 1 large Egg
Add apple/raisin/vanilla mixture and stir until combined.
Add oatmeal and stir until combined.
2 ½ Cups Oatmeal
Pour dough into tart pan. Spread to an even layer with your hands or an offset spatula. Press lightly on the dough.
Bake for 23 - 26 minutes. Place on a rack and allow to cool completely.
Push up on the bottom of the tart pan to remove. Cut into 12 even wedges.