Combine chicken stock, potatoes, swede, parsnips, garlic, bay leaf and thyme in a large pot. Bring to the boil. Reduce heat and cover partially. Simmer until vegetables are very tender, about 30 minutes. Drain.
Transfer vegetables to large bowl. Add 125g butter. Using an electric mixer, beat mixture until mashed but still chunky. Season with salt and pepper. Transfer mashed vegetables to a buttered baking dish.
Melt remaining 50g butter in a heavy large frying pan over medium-high heat. Add sliced onions. Saute until beginning to brown, about 5 minutes. Reduce heat to medium-low. Saute until onions are tender and golden brown, about 15 minutes. Season with salt and pepper. Spread onions evenly over mashed vegetables.
Preheat oven to 190 C / Gas mark 5. Bake, uncovered, for 25 minutes, or until heated through and top begins to crisp.
This dish can be prepared up to 1 day ahead. Cover and refrigerate before baking, then transfer from the fridge straight to the oven the next day.
I've never made a similar dish, and made this one using all the ingredients, except no swede (I had none), and didn't measure anything, and less garlic. But, it still came out super tasty, even without putting it in the oven to bake. Great recipe! - 05 Feb 2016
This was delicious! It's my first time ever trying neeps and tatties and it was fab. We got a HUGE bunch of turnips in our CSA box this week and I wasn't sure what to do with them so I thought I would try this out. We don't have any parsnips so I did change the recipe accordingly and cut it down by a third since I wasn't feeding a crowd. Came out beautifully and tasted delicious. My mom even ate some and complimented the dish! She HATES turnips so take it as a the best of compliments! <3 Thanks for sharing this great recipe. - 24 Mar 2013