Peel and cut 1 medium potato (about 200 grams) into chunks.
Place in a pot, cover with cold water, and add a pinch of salt.
Bring to a boil, then reduce to a simmer and cook 12–15 minutes, until very tender.
Drain well, return the potatoes to the pot for 1 minute to evaporate excess moisture.
Mash until completely smooth and let cool until just warm.
Make the Dough:
In a small bowl, combine warm vegan milk, granulated sugar, and yeast.
Let stand 10 minutes, until foamy.
In a large bowl, mix together: mashed potatoes, melted vegan butter, and salt.
Add the activated yeast mixture and stir.
Add flour and knead the dough 5–7 minutes, until smooth and elastic.
Shape into a ball and place in a greased bowl.
Cover and let rise in a warm place for 1 hour, or until doubled.
Shape the Dough:
Preheat oven to 350°F (175°C).
Grease a 9×9inch (23×23 cm) pan with vegan butter.
Punch down the dough and press it evenly into the pan.
Cover loosely and let rest 20 minutes.
Make the Traditional “Crater” Topping:
With buttered fingers, press deep dimples all over the dough—almost to the bottom, but without tearing it.
Mix the brown sugar and cinnamon, then sprinkle evenly over the top.
Pour the melted butter over the surface.
You can poke again to create more swirling patterns.
Bake and Cool:
Bake 25–30 minutes until golden, bubbling at the edges, and crisp on top.
Cool slightly before slicing.
Serve warm or at room temperature.
Notes
Store Moravian sugar cake covered at room temperature for 2 to 3 days or freeze for up to 3 months. If you’d like, you can reheat slices briefly in the microwave.