Preheat oven to 375 degrees Fahrenheit. Lightly grease a 9x13 casserole dish and set aside.
In a large stock pot, bring salted water to a boil. Cook egg noodles according to package directions for al dente noodles. Drain, rinse, and pour into prepared casserole dish. Set aside.
Meanwhile, in a small saucepan over medium heat, melt butter, stirring frequently. Butter will begin to foam and boil. After 4 to 5 minutes you will see brown flecks appear in the bottom of the pan. Continue to stir until butter is golden and flecks are a medium brown color. Watch closely - butter will brown quickly. Process takes about 5 to 7 minutes. Remove from heat and allow to cool slightly.
In a large bowl, add eggs and whisk to combine. Add sour cream, cottage cheese, salt, pepper, thyme, and sage. Whisk to combine. Last, add your brown butter (including the browned bits at the bottom of the pan) and stir to combine.
Pour egg mixture over noodles and gently stir to coat. Bake for 50-60 minutes, or until casserole is completely set in the center. Leave casserole uncovered for a crunchy noodle crust, or cover with foil for half of baking time for a less crunchy crust.
Remove from oven and allow to set for 15 minutes before serving.
Make ahead - assemble casserole as directed. Before baking, cover and refrigerate for up to 1 day. On day of serving, bake as directed above.
Reheating leftovers - cover baked casserole and refrigerate for 1 to 2 days. Preheat oven to 300 degrees Fahrenheit and bake for 15-30 minutes, or until warmed throughout.
Cottage cheese can be blended in a food processor for a smooth texture, or substituted with heavy cream or half & half for a rich, smooth custard.