Stir milk in a heavy saucepan over medium-high heat until milk starts to show small bubbles, steams, and reaches 85 to 100 degrees F (30 to 38 degrees C). Cool. Stir yeast into cooled milk.
Melt 6 tablespoons butter in a saucepan over high heat; cook until butter is slightly browned, 2 to 3 minutes. Remove from heat and stir 2 tablespoons butter into melted butter. Stir mashed potatoes and 2/3 cup white sugar into butter until well combined.
Beat eggs in a small bowl; add to mashed potatoes mixture and stir well. Pour milk-yeast mixture into mashed potato mixture and stir with a wooden spoon.
Stir flour into potato mixture 1/2 cup at a time, stirring well with a wooden spoon after each addition, until a dough comes together. Turn dough out onto a floured work surface and knead until soft, 1 to 3 minutes. Lightly oil dough with canola oil, place dough in a bowl, cover the bowl with a clean, damp towel, and let rise in a warm place until doubled in size, at least 1 hour.
Melt 1/2 cup butter in a large saucepan over high heat; cook until browned, 2 to 3 minutes. Pour butter into a bowl. Add remaining butter, brown sugar, 1/2 cup white sugar, and cinnamon; mix until filling is well combined.
Roll 1/2 of the dough into a 1/4-inch thick rectangle. Spread 1/2 of the filling over dough rectangle. Cut dough width-wise into 12 equal strips. Roll up each strip and place in a greased 9x13-inch baking dish. Repeat with remaining dough and filling. Cover the baking dish with plastic wrap and refrigerate, 8 hours to overnight.
Preheat oven to 400 degrees F (200 degrees C). Line baking sheets with parchment paper.
Place rolls 4-inches apart on prepared baking sheets.
Bake in the preheated oven, rotating the baking sheets once, until golden and set, 11 to 13 minutes.
Whisk 2 teaspoons vanilla extract and corn syrup together in a bowl. Whisk confectioners' sugar and cream into corn syrup mixture until desired glaze consistency is reached. Drizzle glaze over cinnamon rolls.
