Blend butter, eggs, and vanilla together. Add brown sugar and beat until incorporated.
Add oats, and then raisins. Blend or mix until all ingredients are incorporated and a dough is formed.
Shape the dough into cookies on a parchment lined baking sheet (these cookies will not move or grow, so form them in the shape you want them to take and place as close together as you'd like). Bake at 350 degrees for approximately 15 minutes.
Optional glaze: combine butter, vanilla, and cream, then slowly whisk into powdered sugar until desired consistency is reached. Drizzle over cooled cookies and allow to set.