Platz is a thin fruit cake baked in a shallow rectangular pan and cut into squares. In Prairie Mennonite communities, seasonal platz appears in family and church cooking; rhubarb gives this version its early-summer character.
Family formulas differ. Some spread raw fruit over batter and finish it with streusel; others cook the fruit first. This version keeps the diced rhubarb raw so it softens as the cake bakes, between a tender base and a separate buttery crumb.
A broad pan keeps the cake low and lets the top brown evenly. The batter should be spreadable, not kneaded, and the cake needs a short rest before cutting so the fruit layer settles.
Step 1Remove and discard all rhubarb leaves; use the stalks only. Rinse and dry the stalks, then dice them into pieces about 1 cm wide. Line a 23 × 33 cm pan with parchment and heat the oven to 175°C.
Step 2For the streusel, stir together 94 g flour, 200 g sugar and 0.5 mL salt. Mix in 5 mL vanilla, then pour in 57 g melted butter and toss with a fork until coarse, uneven crumbs form. Set aside.
Step 3Beat 113 g softened butter with 100 g sugar until creamy. Add 1 egg and beat until combined. In another bowl, whisk 250 g flour with 15 mL baking powder and 2.5 mL salt. Measure the egg mixture, then add enough milk to bring the combined volume to 160 mL.
Step 4Add the dry mixture to the butter in two additions, alternating with the egg-and-milk mixture. Mix just until a thick, spreadable batter forms; do not taste it raw. Scrape it evenly into the prepared pan.
Step 5Scatter 360 g diced rhubarb over the batter. Cover it evenly with the streusel without pressing the crumbs into the fruit.
Step 6Bake for 35–40 minutes, until the top is golden and the cake layer is set. Check the centre of the cake, avoiding a rhubarb pocket; it must reach at least 74°C. Cool in the pan for 30 minutes before cutting into 12 squares. Refrigerate leftovers within 2 hours at 4°C or colder; use within 2–3 days or freeze. Reheat leftovers to 74°C.
Serve warm or at room temperature with coffee. For even squares, let the cake cool for 30 minutes before cutting. Bake it up to a day ahead, cool fully, cover and refrigerate. Refrigerate leftovers within 2 hours at 4°C or colder and use within 2–3 days, or freeze for longer storage. If reheating a portion, heat it to 74°C. Use only rhubarb stalks; discard the leaves. Do not eat uncooked batter because it contains raw flour and egg.
Rounded ingredient-based estimate per square from generic food-composition values. The full batch is about 3,867 kcal before rounding, divided by 12. It includes 344 g flour, 300 g sugar, 170 g unsalted butter, 12 g baking powder, 3.6 g salt, about 110 mL milk, one egg, 360 g rhubarb and 5 mL vanilla. Brands and the egg-and-milk measure vary; this is not laboratory analysis or a product label.
Contains wheat, milk and egg. Do not taste the raw batter. Bake the cake until its centre reaches at least 74°C. Use rhubarb stalks only; remove and discard all leaves.
This version layers raw diced stalks over the batter so they soften in the oven. Other platz recipes use a cooked fruit filling.
