- 3 pounds quince, peeled, quartered, and cut into large chunks
- 2 pounds white sugar
- 2 tablespoons lemon juice (optional)
Place quince in a large pot or dutch oven and add enough water to completely cover. Bring to a boil over high heat. Reduce heat to medium-low and simmer until a paring knife can be inserted into middle of quince pieces with no resistance, about 45 minutes.
Drain quince and transfer to a food processor fitted with a steel blade. Process until completely smooth, 1 to 2 minutes.
Transfer quince purée into now empty dutch oven. Stir in sugar and lemon juice, if using. Bring to boil over medium heat. Reduce heat to low and cook until paste has thickened and turned an orange-pink color, about 1 1/2 hours.
Preheat oven to 150°F. Line a 8- by 8-inch baking pan with parchment paper. Pour quince paste into pan, smoothing out top with the back of a spoon. Transfer quince paste to oven and cook for 1 1/2 hours. Remove from oven and let cool completely. Store quince paste in an airtight container in refrigerator for up to 3 months.