GUARANTY

Exhibit 10.3

GUARANTY

This GUARANTY is made as of the 25th day of September 2006 by Bertucci’s Corporation, a Delaware corporation (the “ Guarantor ”), in favor and for the benefit of BUCA, Inc., a Minnesota corporation (the “ Creditor ”).

WHEREAS, the Creditor, BUCA Restaurants 3, Inc. (the “ Company ”), Vinny T’s Acquisition Corporation (the “ Debtor ”) and the Guarantor entered into that certain Stock Purchase Agreement dated as of September 25, 2006 (the “ Stock Purchase Agreement ”) whereby the Debtor will acquire all of the issued and outstanding capital stock of the Company from the Creditor (the “ Transaction ”);

WHEREAS, pursuant to the terms of the Stock Purchase Agreement on the Closing Date (as defined in the Stock Purchase Agreement), the Debtor will issue to the Creditor a Promissory Note in the original principal amount of $3,800,000.00 (the “ Promissory Note ”);

WHEREAS, as a condition to the consummation of the Transaction, the Creditor has required that the Guarantor execute and deliver this Guaranty to the Creditor; and

WHEREAS, the Guarantor desires to see the Transaction consummated and is willing to execute and deliver this Guaranty to the Creditor.

NOW THEREFORE, in consideration of the consummation of the Transaction and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Guarantor unconditionally guarantees full and prompt payment and due performance of all Obligations (as hereafter defined) of the Debtor to the Creditor, its successors and assigns, as herein provided.

Section 1. Obligations Guaranteed.

This Guaranty is a guaranty of the prompt payment and performance of all indebtedness, liabilities and obligations of the Debtor to the Creditor, whether absolute or contingent, due or to become due, now existing or hereafter arising, under the Promissory Note, the Stock Purchase Agreement and any other document, instrument or agreement now or hereafter entered into supplementary thereto (the “ Obligations ”).

Section 2. Nature of Liability.

The liability of the Guarantor hereunder is direct, unconditional and continuing until terminated in accordance with Section 10 hereof. It is a guaranty of payment and performance and not of collection only, and may be enforced without requiring the Creditor to resort to any other person or entity (including, without limitation, the Debtor), right, remedy or collateral. If for any reason any Obligation shall not be paid or discharged promptly when due, the Guarantor will forthwith pay or discharge such Obligation without regard to any counterclaim, set-off,

deduction or defense of any kind which the Debtor or the Guarantor may have or assert, and without abatement, suspension, deferment or reduction on account of any occurrence whatsoever, provided however , that, notwithstanding any other provision of this Guaranty, this third sentence of Section 2 shall not apply if the Debtor or the Guarantor has a counterclaim, set-off, deduction or defense in connection with any breach of a representation, warranty, covenant or agreement of the Creditor under the Stock Purchase Agreement or any Ancillary Agreement (as defined in the Stock Purchase Agreement).

Section 3. Expenses.

If the Creditor incurs any costs, expenses and/or attorneys’ fees to collect under or enforce this Guaranty and the Creditor is successful in collecting under or enforcing this Guaranty, the Guarantor hereby agrees to pay to Creditor, in addition to the Obligations, all reasonable costs, expenses and attorneys’ fees at any time paid or incurred by the Creditor in endeavoring to collect under or enforce this Guaranty, the Obligations or the underlying documents evidencing the Obligations.

Section 4. Limitation of Liability.

Notwithstanding anything in this Guaranty, the Stock Purchase Agreement or the Promissory Note to the contrary, the maximum liability of the Guarantor hereunder shall be the Purchase Price (as defined in the Stock Purchase Agreement), plus any reasonable costs, expenses and/or attorneys’ fees owed under Section 3 of this Guaranty.

Section 5. Event of Default.

If there shall occur an Event of Default (as defined in the Promissory Note), then all payment Obligations under the Promissory Note shall, at the option of the Creditor, immediately become due and payable as though such Obligations had matured by their terms.

Section 6. Consent.

The Guarantor agrees to the provisions of any instrument or other writing evidencing or securing the Obligations. The Guarantor hereby expressly consents to the making, from time to time, and without any notice to the Guarantor, of such extensions, renewals, modifications, indulgences, postponements, settlements and compromises as the Creditor and the Debtor may deem proper with respect to any of the Obligations covered by this Guaranty, including the substitution, exchange, taking or releasing of any or all security or collateral and surrendering of documents and releasing of any party liable directly, indirectly or as guarantor, all without regard to the consideration therefor, and all without notice to the Guarantor. The enforcement of this Guaranty shall not be affected by the neglect or failure of the Creditor to take any action with respect to any security, right, obligation, endorsement or guaranty which it may at any time hold.

Section 7. Waiver of Defenses.

(a) The Guarantor waives the following: notice of incurring of indebtedness and obligations by the Debtor; acceptance of this Guaranty by the Creditor; presentment and demand for payment; protest, notice of protest and not