Butter: I used unsalted dairy-free butter (vegan butter) to keep the recipe dairy-free. If you are not lactose-intolerant, go ahead and use regular butter instead.

Brown sugar: I used light brown sugar, but you may also use dark brown sugar or coconut sugar if you prefer. If you are diabetic or insulin-resistant, I highly recommend using golden granulated monkfruit sweetener (a 1:1 brown sugar substitute that is zero glycemic index and will not raise your blood sugar).

White Sugar: I used white sugar, but you may also use cane sugar if you prefer. If you are diabetic or insulin-resistant, I highly recommend using white granulated monkfruit sweetener (a 1:1 sugar substitute that is zero glycemic index and will not raise your blood sugar).

Eggs: Eggs help to bind the ingredients together, so make sure to add them in. If you are allergic to eggs, or would simply prefer to keep this recipe vegan, you may try using acquafaba or an egg-replacer instead. I personally have not made this recipe without eggs, so I don’t know how it would turn out. (If you do make these gluten-free oatmeal creme pies egg-free, please let me know how they go in the comments below, I’d love to know!)

Vanilla Extract: Adding a bit of vanilla extract gives these cookie sandwiches are lovely flavor, so make sure to add it in!

Gluten-Free Flour Blend: For best results, I recommend using a good-quality gluten-free all-purpose flour blend that is made up of lighter flours/starches (such as rice flour, tapioca starch, corn starch or potato starch). I do NOT recommend using a gluten-free flour blend that is made up of heavier flours (such as garbanzo bean flour). Alternatively, if you are not Celiac or gluten-intolerant, go ahead and use regular flour instead.

Xanthan Gum: Xanthan gum is the replacement for gluten in gluten-free flours, and helps the ingredients to better bind together. If your gluten-free flour blend does not already include xanthan gum, make sure to add it in.

Baking Soda: Baking soda is the only leavening agent in this gluten-free oatmeal cream pie recipe, so make sure to add it in. If you are gluten-free, make sure to use gluten-free baking soda.

Ground Cinnamon: I like adding a pinch of ground cinnamon for a beautiful flavor. If you are not a fan of cinnamon, feel free to leave it out instead.

Oats: You can use either quick oats or old-fashioned oats. If you are Celiac or gluten-intolerant, make sure to use certified gluten-free oats (this is because while oats are naturally gluten-free, they are often processed in the same facilities as other gluten-containing grains and may have cross contamination unless specifically said to be gluten-free).

Powdered Sugar: Powdered sugar, also known as confectioner’s sugar, is basically sugar that has been processed until it is a very very fine powder, and this consistency is required so that the sugar dissolves easily into the butter and you get a creamy buttercream filling. If you are diabetic or insulin-resistant, I highly recommend using powdered monkfruit sweetener (a 1:1 powdered sugar substitute that is zero glycemic index and will not raise your blood sugar).

Unsweetened Almond Milk: I like using an unsweetened version of my homemade almond milk. You may also use other unsweetened dairy-free milk (such as cashew milk, rice milk, oat milk or coconut milk). Alternatively, if you are not lactose-intolerant, go ahead and use regular milk instead.

Eat Immediately or Assemble Before Eating: I recommend serving and enjoying these gluten-free oatmeal cream pies immediately once made, or if you plan to serve them later, you can store the oatmeal cookies and buttercream filling separately in airtight containers (store the buttercream in the fridge, the cookies can be stored at room temperature), and then assembly the cookie sandwiches just before eating.