Melt butter in a Dutch oven over medium. Add onion and 1/2 teaspoon salt; cover and cook, stirring occasionally, until onion is softened, 7 to 8 minutes. Add cabbage; reduce heat to medium-low. Cover and cook, stirring occasionally, until cabbage is slightly tender, about 10 minutes. Stir in brown sugar, onion powder, paprika, red pepper (if using), 1/4 teaspoon black pepper, and 1 1/2 teaspoons salt. Cook, uncovered, stirring often, until deep golden brown, about 15 minutes. Remove from heat. While cabbage cooks, boil egg noodles in a large pot of well-salted water over high until al dente. Drain well, and transfer to a large bowl. Add herbs, oil, lemon zest and juice, 1/2 teaspoon salt, and remaining 1/4 teaspoon black pepper to warm noodles; toss well to coat. Add cabbage mixture; toss until fully combined. Taste and season with remaining 1/2 teaspoon salt, if desired. Divide pasta mixture among plates; garnish with additional herbs. Dollop with crème fraîche, if desired. Serve immediately.