And as protests continue in Ukraine against the government's decision to shelve a landmark pact with the European Union, the 18-year-old Kyiv student has found a new way of putting her kitchen skills to use.
Like millions of Ukrainians who long to see their country join Europe, Marchenko was dismayed when President Viktor Yanukovych walked away from the EU deal last month in favor of closer ties with Moscow.
Her university exams, however, are currently preventing her from joining the protesters camped out on Kyiv's Independence Square, better known among locals as the Maidan.
To make up for her absence, she regularly prepares patriotic-themed biscuits for demonstrators.
"The kitchen on Maidan is very well organized and people bring a lot of food. But there's a shortage of desserts. People usually want something sweet with their tea, especially when they are cold and down. I think sweets always raise people's spirits," Marchenko said.
During her latest baking session, Marchenko made trays full of heart-shaped biscuits which she adorned with the letters UA and UKR, both abbreviations for Ukraine, and yellow and blue glazing representing the national flag.
"I love seeing people smile as they take the biscuits, as they express thanks and say how tasty they are. It's great to see the joy in their eyes," Marchenko said.
Marchenko is one of many Ukrainians who for different reasons cannot spend much time on Maidan but help sustain the protests by keeping demonstrators fed, warm, and in revolutionary spirits.
Words, Deeds Of Support
Since the protests erupted a month ago, sympathizers have been steadily streaming into the square to deliver homemade food, groceries, warm clothes, and other basic necessities.
Many of them take a stroll around Maidan after dropping off their donations at one of the tents that have sprung up on the square, doling out refreshments and words of support to protesters.
Yelena, 75, comes by every other day, usually hauling heavy bags brimming with food and warm clothes.
On one of her recent visits, she was already looking forward to her next delivery.
"I'll make barley kasha. I'll fry onions and throw them into the kasha with some lard, and I'll bring it to Maidan. It should be enough to feed 10 people. I'll also bring bread loaves, otherwise they might still be hungry," Yelena said.
Yelena dreams of a future in Europe for her three children and six grandchildren.
Despite earning just $120 a month answering phones at a local company, she vows to spare no expense for the protesters.
"I'm ready to give whatever I have, however difficult it may be. This is my way of protesting. I come here for the sake of my children and Ukraine, so that its youth lives in Europe, so that we are no longer cheated, so that we receive decent pensions and laws are respected," Yelena said.
Many Ukrainians say they are grateful to protesters for braving subzero temperatures and police truncheons to defend their country's pro-European aspirations.
Riot police have twice attempted to break up the rally in the middle of the night, injuring dozens.
Bonfires, Prayers
Valentina Rokhozhenska, a 41-year-old cook, commutes one hour from work every day to bring homemade food to Independence Square.
It takes her another hour to travel back home.
"People in the cold want to eat warm soup, warm kasha. I bring kasha with gravy and mushrooms, just like in good restaurants. We bring people food and we hope they will stay here until the victorious end," Rokhozhenska said.
While a solution to the political crisis remains elusive, the protesters seem to have everything they need to continue occupying the square for weeks.
Sofia Marchenko hands out cookies in Kyiv.
The food tent is packed high with supplies, bonfires burn bright, a giant stage provides musical entertainment, volunteer doctors treat coughs and runny noses, and army veterans are on site round-the-clock to shield the protesters from police.
Orthodox priests even lead daily prayers calling for peace under a large wooden cross.
The protests, widely dubbed Euromaidan, have drawn praise for their unprecedented level of organization.
Kyiv entrepreneur Dmitro Vasilev is the co-founder of "Plan of Action," an Internet-based initiative to help drum up support for the protests.
He says the Euromaidan is a dramatic improvement from the 2004 Orange Revolution that ushered in a pro-Western government led by Viktor Yushchenko, who stepped down after losing the 2010 presidential election to Yanukovych.
"The organization is much better this time. There is a very clear understanding of how to run this Maidan, where food, clothes, and wood for heating are collected, where people are accommodated, where valuables are stored, there's even a special Internet tent. We had a first experience, and we have since learned a lot from our mistakes," Vasilev said.
Vasilev, Marchenko, Rokhozhenska, Yelena, and countless other Ukrainians appear determined to ensure this Maidan brings long-term democratic change to their country.
Back in her cramped kitchen, Sofia says she is ready to cook as many biscuits as it takes.
"I will continue to bake in my free time. If the protests continue, I will do everything in my power to support them," Marchenko said.
Tom Balmforth reported from Kyiv. Claire Bigg reported and wrote from Prague
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